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Introduction to COMSOL Multiphysics®

1. Switzerland COMSOL Multiphysics GmbH Technoparkstrasse CH 8005 Z rich 41 0 44 445 2140 41 0 44 445 2141 info ch comsol com www ch comsol com Introduction to COMSOL Multiphysics 1998 2011 COMSOL United Kingdom COMSOL Ltd Broers Building 21 J J Thomson Avenue Cambridge CB3 OFA 44 0 1223 451580 44 0 1223 367361 info uk comsol com www uk comsol com United States COMSOL Inc New England Executive Park Suite 350 Burlington MA 01803 781 273 3322 78 273 6603 i COMSOL Inc 10850 Wilshire Boulevard Suite 800 Los Angeles CA 90024 310 441 4800 310 441 0868 i COMSOL Inc 744 Cowper Street Palo Alto CA 94301 1 650 324 9935 650 324 9936 info comsol com www comsol com X Mm BY For a complete list of international representatives visit www comsol com contact Home Page www comsol com COMSOL User Forums www comsol com community forums Protected by U S Patents 7 519 518 7 596 474 and 7 623 991 Patents pending This Documentation and the Programs described herein are furnished under the COMSOL Software License Agreement www comsol com sla and may be used or copied only under the terms of the license a
2. T ModelBuilder 2 gt E s ETE TO 4 busbar mph root gt Global Definitions 4 Model 1 mod1 gt Definitions YA Geometry 1 amp Materials 4 Joule Heating ih PO Jda Joule Heating Model C2 Ell Electromagnetic Heat Source D bs i 3 Infinite Elements gt D gt Th c Initial Values gt Inl Heat Transfer in Solids gt amp Mesh Electric Currents gt W Study 1 Results o Boundary Electromagnetic Heat Source Periodic Condition Heat Transfer in Solids gt p Electric Currents gt ta Pairs gt a Edges gt 5 3 a Points Mita gt Delete Delete G Temperature Thermal Insulation Outflow Symmetry Convective Cooling Heat Flux Surface to Ambient Radiation Boundary Section Domain Section 3 In the Heat Flux Settings window select All boundaries from the Selection list Assume that the circular bolt boundaries are neither heated nor cooled by the surroundings In the next step these boundaries are removed from the heat flux selection list which leaves them with the default insulating boundary condition for the Heat Transfer Interfaces 8 Thorough Example The Busbar Gad Settings _ 4 o Heat Flux Boundary Selection Manual All boundaries b Owerride and Contribution Rotate the busbar to view the back Click one of the circular titanium bolt surfaces to highlight it in green Right click an
3. 17 Right click Laminar Flow and select Outlet Fluid Properties G3 Volume Force ace wget S b E Mesh1 b lt a Study 1 o Inlet D M hes ta Outlet Wall Symmetry in a a 18 In the Graphics window select the Cross check Boundary 5 outlet boundary 5 and right click just like in step The last step is to add symmetry boundaries You can assume that the flow just outside of the faces of the channel is similar to the flow just inside these faces This is correctly expressed by the symmetry condition 54 Adding Physics to a Model 19 Right click Laminar Flow and l select Symmetry a P c Fluid Properties Volume Force Initial Values gt E Me s Inlet gt 222 Study e 7 Outlet a Wall amp Ge Symmetry fe Open Boundary 2 In the Graphics window click one of the blue faces in the figure and right click to add it to the Selection list Continue with the three other faces Cross check Boundaries 3 4 and 48 When you know the boundaries you can click the Paste button and enter the information In this Selection 1 3 4 43 example enter 1 3 4 48 in the Paste selection Window Click OK and the boundaries are automatically added to the Selection list The next step is to change the mesh slightly in order to get a quick solution The current mesh settings would take a relatively long time to solve
4. 9 Be sure to Inspect the Material Contents F section in the Settings window All the 8 Settings gt 8 Material Browser o properties used by the physics interfaces Material should have a green check mark w Santa sae 10 Close the Material Browser Geometric entity level Material Browser Material Properties G Material Contents Property Name w Electric conductivity sigma Heat capacity at consta Cp Relative permittivity epsil Density rho 7 Thermal conductivity k Relative permeability mur Coefficient of thermal alpha Young s modulus E Poisson s ratio nu PHYSICS The domain settings for the Joule Heating physics interface are complete now that you have set the material properties for the different domains Next you will set the boundary conditions for the heat transfer problem and the conduction of electric current 6 Thorough Example The Busbar 1 In the Model Builder expand the Joule Heating node to examine the default physics interface nodes The equations that COMSOL solves are displayed in the Equation section of the Settings window The equations change based on the Equation form selected The default equation form is inherited from the study added in the Model Wizard For the Joule Heating node COMSOL displays the equations solved for the temperature and electric potential The domain level Joule Heating Model I node ha
5. The function name is its identifier for example wv 1 A waveform function is a periodic function with one of several characteristic shapes sawtooth sine square or triangle The function has one argument It can 92 Supported External File Formats CALL argument within parenthesis For example step1 x The name of the function with a single argument within parenthesis For example trit x The name of the function with a single argument within parenthesis For example wvi1 x Keyboard Shortcuts SHORTCUT WINDOWS LINUX i F2 F5 F8 Del Alt left arrow Alt right arrow Ctrl A Cirle Ctrl V Ctrl Z Signa Ctrl up arrow Ctrl down arrow Ctrl Tab Ctrl Shift Tab Ctri Altt left arrow Ctrit Alt right arrow Ctrit Alt up arrow Ctrl Alt down arrow Shift F 10 or Windows only Menu key Ctrl Space SHORTCUT MAC FI F2 F5 F8 Del Ctrl left arrow Ctrl right arrow Command A Command C Command V Command Z Ctrl Shift Z Command up arrow Command down arrow Ctrl Tab Ctrl Shift Tab Command Alt left arrow Command Alt right arrow Command Alt up arrow Command Alt down arrow Ctri F 10 Ctrl Space ACTION Display dynamic help for the selected node Rename the selected node file or folder Update solution Build the geometry build the mesh or update the plot Delete a node Move to the previously selected node in the Model Bu
6. ng User Defined Library ii Add Material Library Rename Selected Phase 6 Remove Selected t3 Enter New Name Le Name My Materials 36 Material Properties and Libraries Mesh Sequences A model can contain different mesh sequences to generate meshes with different settings These sequences can then be accessed by the study steps In the study you can select which mesh you would like to use in a particular simulation In the busbar model a second mesh node is added to create a mesh that is refined in the areas around the bolts and the bend You do this by increasing the mesh resolution on curved surfaces Locate and open the file busbar mph if it is not already open on the COMSOL Desktop ADDING A MESH To add a second mesh node right click the Model I node and select Mesh amp This creates a Meshes parent node that a V3 busbar mph root contains Mesh I and Mesh 2 ae re gt E Global Definitions a X Model 1 mod1 gt Defi a Add Physics Fi Geo a Mesh gt g Mat a X Joul amp Delete Delete CJ amp Rename F2 to Dad FE Properties 2 Click the Mesh 2 node In the Settings window under Mesh Settings select User controlled Gail Settings Bo mesh as the Sequence type amp Mesh Mesh Settings Sequence type User controlled mesh In the Model Builder under Mesh 2 click Size 43 The stars in the upper right corner of the icons indicate that
7. Conjugate Heat Transfer Radiation a X Electromagnetic Heating iim Induction Heating ih Joule Heating fi YS Model Wizard E Select Study Type ch Studies a ae Preset Studies b Frequency Stationary fe Frequency Transient DM Frequency Domain Ox Stationary b Time Dependent gt Custom Studies GLOBAL DEFINITIONS If you want to draw the geometry yourself the Global Definitions brnch is where you define the parameters If you would prefer to load the geometry from a file you can just browse through this section and then skip to Geometry on page 10 The Global Definitions node in the Model Builder stores Parameters Variables and Functions with a global scope You can use these operations in several models In this case there is only one Model node where the parameters are used Since you will run a geometric parameter study later in this example define the geometry using 2xrad_ tbb parameters from the start In this step enter parameters for the length for the lower part of the busbar L the radius of the titanium bolts rad_1 the thickness of the busbar tbb and the width of the device wbb You will also add the parameters that control the mesh mh a heat transfer coefficient for cooling by natural convection htc and a value for the voltage across the busbar Vtot Under Global Definitions click the Parameters node ri In the Parameters table
8. Introduction to COMSOL Multiphysics VERSION 4 2a NE COMSOL Benelux COMSOL BV R ntgenlaan 37 2719 DX Zoetermeer The Netherlands 31 0 79 363 4230 31 0 79 361 4212 info comsol nl www comsol nl 10 amp By Denmark COMSOL A S 45 88 70 82 00 amp 45 88 70 82 88 gt lt info comsol dk www comsol dk 358 9 2510 400 amp 3589 2510 4010 gt lt info comsol fi www comsol fi 33 0 4 76 46 49 OI 33 0 4 76 46 07 42 info comsol fr www comsol fr Germany COMSOL Multiphysics GmbH 49 551 99721 0 49 551 99721 29 info comsol de www comsol de India COMSOL Multiphysics Pvt Ltd Esquire Centre C Block 3rd Floor No 9 M G Road Bangalore 560001 Karnataka 9 80 4092 3859 9 80 4092 3856 info comsol co in www comsol co in X im c Italy COMSOL S r l Via Vittorio Emanuele Il 22 25122 Brescia 39 030 3793800 39 030 3793899 info it comsol com www comsol it Norway COMSOL AS Postboks 5673 Sluppen Sondre gate 7 NO 7485 Trondheim 47 73 84 24 00 47 73 84 24 Ol info comsol no www comsol no ID x m BY Sweden COMSOL AB 46 8 412 95 00 amp 46841295 10 gt lt info comsol se www comsol se
9. MATERIALS The chosen bolt material and tool steel are important characteristics of this contact problem Here is how to choose them in COMSOL Easy Example The Wrench 79 Under Model I right click Materials and select Open Material Browser or select View gt Material Browser 2 Inthe Material Browser under MET Model Builder gt E s Et EH zj 4 Untitled mph root Global Definitions a i Modell mod b Definitions gt A Geometry 1 8 Materials b SEA Soli SM gt Results Material 8 Open Material Browser Fal Thenamic Heln Fi Gea Settings 88 Material Browser x m Materials expand the Built In folder Scroll D a down to find Structural Steel right click and select Add Material to Model 3 Examine the Material Contents section to see how COMSOL categorizes available material information with respect to What the active physics interface requires 80 Easy Example The Wrench Material Browser Materials 8 Nimonic alloy 90 Nylon 8 Lead Zirconate Titanate P7T 5 8 Silica glass Silicon 8 Polysilicon 8 Solder 605n 40Pb 8 Steel AISI 4340 Structural steel F Add Material to Model Remove Selected Orientation variation Material Contents Property Name Value Unit Density rho T850 kg m kag Young s modulus E 200e9 Pa Pa w Poisson s ratio nu 0 33
10. click the first row under Name and enter L 2 Click the first row under Expression and enter the value of L 9 em You can enter any unit inside the square brackets 3 Continue adding the other parameters L rad_1 tbb wbb mh htc and Vtot according to the Parameters list It is a good idea to enter descriptions for variables in case you forget or share the model with others 38 Settings P Parameters Parameters Expression cm 6 mm 5 mm 5 cm 6 mm 5 Wirmn 2 K 20 mV t y e p Mame Vtot Expression 20 mV Description Busbar voltage Thorough Example The Busbar 9 GEOMETRY In Global Definitions you learned how to enter parameters in preparation for drawing the busbar geometry To learn how to use the COMSOL geometry tools and draw the busbar go to Geometry Sequences on page 66 To save time you can also load the model geometry from the Model Library Once you have created or imported the geometry you can then experiment with different dimensions and update the values of L tbb or wbb and rerun the geometry sequence Select Model Library IE from the main View menu 2 n the Model Library select COMSOL Multiphysics gt Multiphysics gt busbar_geom lo open double click right click and select Open or click the Open button Now you can experiment with different dimensions 0 Thorough Example The Busbar Material
11. i Results Ee Properties 1 Rename Model CX New name Busbar Ce 2 In the Rename Model window enter Busbar Click OK and save the model 32 Parameters Functions Variables and Model Couplings DEFINING MODEL COUPLINGS Global Definitions Pi Parameters a Variables 1 i Busbar modi Definitions faw Integration 1 intop1 E gt Boundary System 1 sys1 m The next steps are for information only and you do P not need to reproduce them unless you want to h m w Click the Definitions node under Busbar mod to b introduce a Model Coupling that integrates any Busbar mod variable at the bolt boundaries facing J View1 the electric device You can use this coupling to A eae Materials define a Variable in Global Definitions that _ amp Joule Heating jh E Mesh1 calculates the total current This variable is then a BD Electtic Device moa2 globally accessible and could for example form a Definitions boundary condition for the current that is fed to A cia Heat Transfer ht Electrostatics es the electric device in the Electric Device mod2 node The Model Couplings in Definitions have a wide range of use The Average Maximum 4 and Minimum model couplings have applications in generating results as well as in boundary conditions sources sinks properties or any other contribution to the model equations The Probes are for monit
12. Element Size Parameters element size are limited The Minimum Maximum element growth rate element size is slightly smaller than the a maximum size Resolution of curvature 0 2 The resolution of curvature determines the Resolution of narrow regions number of elements on curved edges the T larger this resolution value is the more elements are used The Maximum element 22 Thorough Example The Busbar growth rate determines how fast the elements should grow from small to large over a domain The larger this value is the larger the growth rate A value of 1 does not give any growth The resolution of narrow regions works in a similar way to the resolution of curvature 4 Click the Build All button in the Size Settings window to create the mesh as shown in this figure x ee e QQRQ STUDY To run a simulation in the Model Builder right click Study I and choose Compute Compute Update Solution Parametric Sweep Study Steps The Study node automatically defines a solution sequence for the simulation based on the selected physics and the study type Show Default Solver Rename The simulation only takes a few seconds to solve Thorough Example The Busbar 23 RESULTS The default plot displays the temperature in the busbar The temperature difference in the device is less than 10 K due to the high thermal conductivity of copper and titanium The temperature variations are
13. The local displacement due to thermal Unit expansion is displayed by COMSOL as a i surface plot Description Total displacement Range Manual color range Next add exaggerated deformation information 2 In the Model Builder under Results gt 3D Plot Group 2 right click the Surface node Ry and add a Deformation Save the model mt WE busbarlLmph COMSOL Multiphysics 0608 62 08 4 v EAE AT fi Model Duder E s rt gt D eip st O Ee craps CEEE A EE Eseti ann a WF bustarlmph froci gt ao r Babai efirdan Deformation z E a Diii T Epeka j pompiere 2 Jouke Hering g z a P Sota Mechanics revit oe b ES Linge Paste Material Model at Free Eo ija Wales l E fied Ciria 1 ES Mesh f Rudy 1 Deeplecerert field PAlsterial a Baeuke G0 Dons Sets Enh fu Dered Values Tables teste factor O 1l T sss aes E Termpersture yh a i I Peet Gere d e i COMSOL 420 108 BS Expert ea Repons Deed file buert SAT ME JESL ME You can also plot the von Mises and principal stresses to assess the structural integrity of the busbar and the bolts 44 Adding Physics to a Model FLUID FLOW After analyzing the heat generated in the busbar and possibly the induced thermal stresses you might want to investigate ways of cooling it by letting air flow over its surfaces When you have the CFD Module or the Heat Transfer Module the C
14. a js Work Plane 3 fwp3 4 A Geometry i Circle 1 ct Copy 1 fcopy1 p bY View 4 RS Extrude 3 ext3 a Form Union fin 76 Geometry Sequences Easy Example The Wrench Torquing a Wrench Working with hand tools gives you a practical introduction to basics of engineering At some point in your life It is likely you have tightened a bolt using a wrench This exercise takes you through a model that analyzes this basic task going into detail about the associated geometric tolerances torque specs and the intrinsic contact problem In principle a bolt replaces the need for external fastening by providing an internal clamping force via pretension The tensile stress in a bolt is produced when It Is torqued into a matching threaded hole or nut The magnitude of this stress depends on many factors such as material selection assembly configuration and lubrication Control of these parameters becomes the focus of much engineering effort especially in critical applications such as automotive engines brakes aircraft and structural installations The following model presents both a bolt and a wrench at the moment of installation MODEL WIZARD n the Model Wizard select 3D and click Next i US Model Wizard aga Select Space Dimension gt a ex c O 2D axisymmetric 2D 91D axisymmetric 1D oD Easy Example The Wrench 7 2 n Add Physics select Structural Mechanics gt Solid itj Solid Sm
15. 1 Relative permeability mur 1 1 Heat capacity at constant Cp ATS ikg K Mikg Thermal conductivity k 44 5 Witm Wi Electrical conductivity sigma 4 032e6 S Sm Relative permittivity epsilonr 1 1 GLOBAL DEFINITIONS Parameters In the Model Builder right click Global Definitions and choose Parameters i 2 Go to the Settings window for Parameters 3 Locate the Parameters section In the Parameters table enter the following settings NAME EXPRESSION DESCRIPTION F 150 N Applied force DOMAIN PHYSICS AND BOUNDARY CONDITIONS With the geometry and materials defined you are now ready to revisit the governing physics introduced in the Model Wizard section I In the Model Builder 4 Y wrench mph root right click Solid Mechanics gt Global Definitions a 4 Modell modi solid and select Fixed a ea Constraint YA Geometry 1 gt 8 Materials gt Solid Mechanics solid i ES Mesh1 Linear Elastic Material Model rdo e gt Sq Study 1 Hyperelastic Material Model gt Results m i l L Viscoelastic Material Model Cam Clay Material Model t Body Load 3 Initial Values More p a Free Fixed Constraint oe Prescribed Displacement o Prescribed Velocity Easy Example The Wrench 8 2 Rotate the geometry by left clicking and dragging into the position shown Then left click the cut face of the partially modeled bolt w
16. Geometry 1 b gt 2 Work Plane 1 wp BS Extrude 1 ext b gt js Work Plane 2 wp2 BS Extrude 2 fext2 f js Work Plane 3 wp BS Extrude 3 ext3 4 84 Form Union fin ah AAt aalo o 5 In the Graphics toolbar click the Zoom Extents button to see the wider busbar in the Graphics Window mE 4 Finalize Build All Finalize Finalization method Relative repair tolerance 1e 6 ch Graphics Thorough Example The Busbar wbb 5cm G wbb 10cm 6 To rotate the busbar left click and drag it in the Graphics window To move it right click and drag Io zoom in and out center click and hold and drag To get back to the original position click the Go to Default 3D View button on the Graphics toolbar 7 Return to the Parameters table and change the value of wbb back to 5 cm 8 In the Model Builder click the Form Union node 4 and then the Build All button amp rerun the geometry sequence 9 On the Graphics toolbar click the Zoom Extents button p to 10 Save your work as busbar mph Experienced users of other CAD programs are already familiar with this approach since all major CAD platforms include parameterized geometries To support this class of users and to avoid redundancy COMSOL offers the LiveLink family of products These products connect COMSOL Multiphysics directly with a 2 Thorough Example The Busbar P Parameters
17. The flexible nature of the COMSOL environment facilitates further analysis by making what if cases easy to set up and run You can take your simulation to the production level by optimizing any aspect of your model Parameter sweeps and target functions can be executed right in the user interface From start to finish COMSOL is a complete problem solving tool As you become a more experienced user of COMSOL your confidence in computer simulation will grow You will become a more efficient modeler and the results will show It The remainder of this introduction is dedicated to give you a strong start toward this goal After a general introduction to the user interface several tutorials will take you step by step through sample models that highlight important features The informative charts give you an idea of COMSOL s capability by associated files functions and built in options By the end you will be well on your way to reaping all the benefits that COMSOL has to offer 2 Introduction Capture the Concept COMSOL Multiphysics version 4 2a brings an unprecedented level of clarity to your simulation work by giving you both an organized model overview and a streamlined model building process The COMSOL user interface reduces clutter and redundant tasks so your attention can be focused on the substance of your design studies resulting in increased productivity Naturally COMSOL continues in its tradition of powerful solvers and flexib
18. and you can always refine it later So for now make the mesh coarser Adding Physics to a Model 55 COARSENING THE MESH I In the Model Builder expand the Mesh I node amp then ss Meds click the Size node Aj AF Size Free Tetrahedral 1 2 In the Settings window under Element Size confirm that Predefined and Normal are selected 234 Settings 3 Click the Build All button 44 Size You can assume that the flow velocity is Element Size Calibrate for large enough to neglect the influence of the General physics temperature increase in the flow field 7 Predefined Normal It follows that you can solve for the flow field iiai first and then solve for the temperature b Flement Sive Parameters using the results from the flow field as input You implement this with a study sequence RUNNING A STUDY SEQUENCE FLUID FLOW AND JOULE HEATING When you solve the flow field first and then the temperature field it yields a weakly coupled multiphysics problem The study sequence described in this section automatically solves such a weak coupling In the Model Builder cue a amp Study 1 right click Study lt 2 and Z st Compute select Study gt A Reu me l 7 ae Parametric Sweep E Steps gt Stationary t to aadd a Study Steps gt E Stationary second stationary study Show Default Solver ti Time Dependent step ti Eigenfrequency Next you need to connect the c
19. any solution you can create an image that is displayed by COMSOL when browsing for model files From the File menu select Save Model Thumbnail There are two other ways to create images from this plot One way is to z click the Image Snapshot button p in ag m the Graphics toolbar to directly create an image You can also add an Image node to a Report by right clicking the plot group of interest The second option means you can reuse the Image Settings if you update the model The temperature distribution is symmetric with a vertical mirror plane running between the two lower titanium bolts and running across the middle of the upper bolt In this case the model does not require much computing power and you can model the whole geometry For more complex models you can consider using symmetries in order to reduce the size of the model The next Surface plot generated shows the current density in the device 6 In the Model Builder right click Results IT Model Builder gt E s Et TO and add a 3D Plot Group Right click 3D a X busbar mph root b Global Definitions Plot Group 2 and add a Surface node gt Model 1 modi gt SB Study1 4 Results gt HH Data Sets 285 Derived Values 8 Tables gt Temperature jh b AR 3D Plot Group 2 T Export Plot F8 EE Reports Plot In p B Volume HE Arrow Volume Surface Slice Isosurface E Arrow Surface 7 In the Settings
20. available as a weak constraint and as a strong pointwise constraint Physics Interfaces With New Names NEW NAME Transport of Diluted Species Transport of Concentrated Species Laminar Flow Electric Currents Heat Transfer in Solids Heat Transfer in Fluids Solid Mechanics Deformed Geometry NAMES IN 3 5A Convection and Diffusion Diffusion Electrokinetic Flow and Nernst Planck without Electroneutrality Maxwell Stefan Diffusion and Convection Incompressible Navier Stokes non Newtonian Flow General Laminar Flow and Stokes Flow Conductive Media DC Quasi Statics Electric Conduction General Heat Transfer Convection and Conduction General Heat Transfer Solid Stress Strain Axial Symmetry Stress Strain Plane Stress and Plane Strain Parameterized Geometry COMMENTS The Transport of Diluted Species interface includes all transport mechanism for mass transport of diluted species The functionality for migration through electrophoresis and electroosmosis is only available in the Chemical Reaction Engineering Module and MEMS Module The Transport of Concentrated Species interface also includes two other diffusion models for mass transport of concentrated species the mixture averaged diffusion model and a diffusion model based on Fick s law The Laminar Flow interface includes all variants of laminar flow Some of the functionality is only available in the Chemical Reaction Engin
21. have completed a basic multiphysics simulation The next sections are designed to increase your understanding of the steps you implemented up to this point as well as to extend your simulation to include other relevant effects like thermal expansion and fluid flow 28 Thorough Example The Busbar Parameters Functions Variables and Model Couplings This section explores working with Parameters Functions Variables and Model Couplings For this purpose you can continue working with the same model from the previous section Locate and open the file busbar mph if it is not already open on the COMSOL Desktop Global Definitions and Definitions contain functionality that helps you to prepare model inputs and model couplings and to organize simulations You have already used the functionality for adding Parameters to organize model inputs in Global Definitions on page 9 Functions available as both Global Definitions and Definitions contain a set of predefined functions that can be useful when you set up multiphysics simulations For example the Step function can create a smooth step function for defining different types of switches To illustrate using functions assume that you want to add a time dependent study to the busbar model by applying an electric potential across the busbar that goes from 0 V to 20 mV in 0 5 seconds For this purpose you could use a step function to be multiplied with the parameter Vtot Add a func
22. largest on the top bolt which conducts double the amount of current compared to the two lower bolts The temperature is substantially higher than the ambient temperature of 293 K Left click and drag the image in the Graphics window to rotate w and view the back of the busbar 2 On the Graphics toolbar click the Go to Default 3D View button j You can now manually set the color table range to visualize the temperature difference in the copper part 24 Thorough Example The Busbar 3 Under the Results gt Temperature node j click the Surface I node In the Settings window click Range and then select the Manual color range check box Enter 323 in the Maximum field Click the Plot button a a Settings gt 5 Surface v Data Data set From parent Expression Expression T Unit K E Description Temperature Range Manual color range Minimum 322 6174 Maximum 323 i 4 On the Graphics toolbar click the Zoom Extents button K cb Graphics x Br Q A E d v by bz amp Thorough Example The Busbar 25 D Graphics 2O 9 ev by be lx ita m O Surface Temperature K 330 75 330 329 328 327 326 320 324 NPE 323 F 322 72 5 Left click and drag in the Graphics window to rotate the busbar and amp view the back Surface Temperature K 2 1 A 330 75 Create a Thumbnail Image for the Plot x107 20 With
23. p mie Fasta wT H tapers Menge rr pmpa E i a z RESET Pa ay ag Model Builder with Model Tree Messages Progress and Numerical Results Capture the Concept 3 Customize You can easily customize the layout of these windows on the Desktop to suit your particular work habits All windows can be positioned and sized in any way They can be detached from the Desktop and moved back and forth between computer displays These settings can be saved as preferences for the next time COMSOL Multiphysics is opened Dynamic Help Model Builder and Settings Graphics Window Model Library Material Browser Streamline The user interface streamlines the modeling workflow with the Model Builder Containing a Model Tree the Model Builder does much more than outline your model It is a graphical programming environment that gives you dynamic control of your procedures and simulations By following along the nodes within the Model Builder you will experience a smoother more direct and less cumbersome way to specify your models 4 Capture the Concept Look at this example of the Model Builder Notice how every step of the modeling process from defining global variables to the final report of results is easy to see Ty Model Builder 4 i busbar mph root 4 Global Definitions Pi Parameters 4 4 Modell modi Definitions b A Geometry 1 b Materials Joule Heating jh gt m Electric Pi Groun
24. s field 4 In the same Settings window under Expression select the Description check box and enter Principal Stress Field S1 Under Levels set the Total levels to 12 Under Coloring and Style select Filled as the Contour type 86 Easy Example The Wrench Expression Expression solid spl Unit N m 2 Description Principal Stress Field 1 Parameters Name solid refpntx solid refpnty solid refpntz Levels Description Reference po Reference po Reference po Entry method Number of levels O Total levels 12 Coloring and Style O Contour type Coloring Color table r Filled g 5 Click the Plot button and rotate the geometry to approximately the orientation shown in the figure You can see that the tensile stress concentrates at the handle s top toward the open end which is consistent with the downward force applied to the socket Also note high stresses in the head to shank transition of the bolt Easy Example The Wrench 87 Supported External File Formats After completing a design study as you have done you often want to use the results in some other context For instance you may want to output an optimal geometry in a dedicated CAD format In fact the broadly applicable nature of multiphysics simulation brings with it the need for interaction with many other scientific computing platforms For this reason COMSOL Multiphysics provide
25. 1 K to 318 K as the width of the busbar increases from 5 cm to 10 cm To further analyze these results you can plot the average temperature for each width VIEWING THE RESULTS I Right click Results and add a ID Plot Group jwz Then right click ID fidsettings I Global Plot Group 4 and select Global jw In the Settings window select Solution 2 f from the Data set list Data set 2 Select From list as the Parameter Parameter selection wbb selection wbb Click the first row in Parameter values the Expressions column and enter aveop1 T You use a similar syntax to calculate the average of other quantities y Axis Data 5 Expression Unit Description aveopl T K X 3 Click the Plot button and save the model 322 aveop1 T ww b co Q D Average Temperature K Q9 b e 312 310 Width m In the plot the average temperature also decreases as the width increases This indicates that the goal of a lower operating temperature would be fulfilled by using 62 Parameter Sweeps and Parallel Computing a wider busbar Of course this may also increase the total mass and therefore the cost of the busbar This suggests an optimization problem for you to consider The subject of parameter sweeps naturally raises the question of parallel processing it would be efficient if all parameters were solved simultaneously Parameter Sweeps and P
26. Browser Model Library Model Library Update Selection List Messages Progress Log Results it w k Model Builder Node Label Desktop Layout ead Settings I Model Library 53 5 CAB Pla Model Library Search 4 W COMSOL Multiphysics gt Acoustics gt F Chemical Engineering gt Diffusion gt F Electromagnetics gt F Equation Based Models gt F Fluid Dynamics gt F gt Geophysics gt Heat Transfer gt F gt Multidisciplinary Models 4 Multiphysics busbar busbar_box busbar geom free con Open MP aana Model PDF thermal_z i Onuantum Me Dynamic Help F1 a Open Model PDF ml 3 Under Global Definitions click the Parameters node Fi r Parameters In the Settings window select the wbb parameter s Expression column and enter Parameters 10 cm to change the value of the width i Expression Value wbb giem 0 09 m 6 mm 0 006 rm 5 mm 0 005 rm amp 0 05 m 6 mm 0 006 rm 5 W m 2 K 5 Wilm K 20 mV 0 02 V Expression 5 cm Description Busbar width 4 n the Model Builder click the Form Union node 4 and then the Build All button rerun the geometry sequence Ip Model Builder p Et 11 7 O bed Settings _ 4 busbar mph root 4 Global Definitions Pi Parameters 4 i Modell rmodt b Definitions a A
27. Material Databases FILE FORMAT READ WRITE NASA file dat Yes No CHEMKIN dat Yes No CAPE OPEN direct connection n a n a Requires Chemical Reaction Engineering Module Mesh FILE FORMAT READ WRITE NASTRAN Bulk Data nas bdf nastran dat Yes No VRML vI vrml vrl Yes No STL stl Yes No Numerical Data Images and Movies FILE FORMAT READ WRITE Plain text txt Yes Yes Copy and paste spreadsheet format No Yes JPEG jpg No Yes PNG png No Yes BMP bmp No Yes EPS eps 2D graphs No Yes Animated GIF gif No Yes Adobe Flash swf No Yes AVI avi No Yes Available for Windows only Supported External File Formats 89 Programming Languages FILE FORMAT READ WRITE MATLAB Model M File m Yes Yes MATLAB Function m Yes No Java Model Java File java Yes Yes C Function Yes No Requires LiveLink for MATLAB Interpolation Data Formats FILE FORMAT READ WRITE Spreadsheet Yes Yes Grid Yes No Sectionwise Yes Yes Built in Functions FUNCTION ARGUMENTS AND DEFINITION CALL Analytic The function name is its identifier for The name of the function with example an comma separated arguments within The function is a mathematical parenthesis For example expression of its arguments ani x y Example Given the arguments X and Y its definition is SLN xX COS y The function has arbitrary number of arguments Gaussian Pulse The function name is its identifier for The name of the functi
28. Parameters Expression Value 9 cm 0 09 m lmm 0 006 m Simm 0 005 m 0 05 m mm 0 006 m 5 W m 2 K 5 W m K 20 mV 0 02 V tise SB Name wbb Expression 5 cm Description Busbar width separate CAD program so that all parameters specified in CAD can be interactively linked with your simulation geometry The current product line includes LiveLink interfaces for SolidWorks Inventor Pro ENGINEER Creo Parametric AutoCAD and SpaceClaim It is also worth noting that the LiveLink interface for MATLAB is available for those who want to Incorporate a COMSOL Multiphysics model into an extended programming environment After completing the geometry for your model it is time to define the materials MATERIALS The Materials node stores the material properties for all physics and all domains in a Model node The busbar is made of copper and the bolts are made of titanium Both these materials are available from the Built In material database In the Model Builder right click Materials and select Open Material Browser or select Material View gt Material Browser ST g Open Material Browser gt amp Joule ES Mesh El Dynamic Help Fl 2 In the Material Browser expand the Built In materials folder locate Copper right click and select Add Material to Model 294 Settings 2 Material Browser 3 gt 7O O Material Browser Materials Brick Cast i
29. Sequences 6 Under Work Plane I right click Geometry A a and select Fillet In the Graphics window click point 3 the inner corner and right click to add it to the Vertices to fillet list Enter tbb in the Radius field This takes care of the inner corner Fillet Points Vertices to fillet Radius O Radius tbb m 7 For the outer corner right click Geometry i la a A and select Fillet j l Fillet In the Graphics window click point 6 the outer corner and right click to add it to the Vertices to fillet list Enter 2 tbb in the Vertices to fillet Radius field Click Build Selected 4 ww F Radius amp Radius 2 tbb m Geometry Sequences 69 The result should match this figure o 0 09 0 08 0 07 0 06 0 051 0 04 0 03 0 02 0 02 0 01 0 0 01 0 02 0 03 0 04 0 05 0 06 0 07 0 08 0 09 0 1 0 11 0 12 Next you extrude the work plane to create the 3D busbar geometry 8 In the Model Builder right click Work Plane I amp 84 Settings and select Extrude amp In the Settings window enter wbb in the Distances from Work Plane table ds to extrude to the width of the profile General The table allows you to enter several values in Work plane order to create sandwich structures with Input objects different layer materials In this case only one wpl db extruded layer is needed Click Build Selected f Click the Zoom Extents button on
30. Solids Electric Currents gt o Boundary Current Source Pairs gt Gp Ground T o Electric Potential t Normal Current Density Mictrih Points v 7 Click the circular face of the upper titanium bolt to highlight it and ee oc oud right click anywhere to add it to the Selection list 8 In the Settings window enter Vtot in Hectric Potential the Electric Potential field aiii Electric potential The last step is to set the two remaining bolt surfaces to ground 20 Thorough Example The Busbar 9 In the Model Builder right click the Joule Heating node jx In the boundary section of the context menu select Electric Currents gt Ground FT Model Builder 4 busbar mph root b Global Definitions 4 Modell mod1 gt Definitions gt YA Geometry 1 b 8 Materials 4 amp Joule Heating Model C3 Electromagnetic Heat Source Infinite Elements Initial Values Heat Transfer in Solids Electric Currents gacrwrror o Boundary Electromagnetic Heat Source o Periodic Condition Heat Transfer in Solids Electric Currents Pairs Ground Edges gt c Electric Potential 10 In the Graphics window click one of Fcc Bonaduce cand 1s the remaining bolts to highlight tt Right click anywhere to add It to the Selection list Repeat this step for the last bolt 1 On the Graphics toolbar click the Go to Default 3D View b
31. You can also add comments and rename the function to make it more descriptive 5 Right click the Step I node r inthe ee roo Model Builder and select Properties s Global Definitions Pi Parameters T Step 1 step1 F i Model 1 La Copy Duplicate M Delete Delete 4 Joule Disable 1 Rename F2 Properties PH rT enam Hela F 6 In the Properties window enter the E P Properties mi BA ao required information a Step The Global Definitions and Definitions nodes l Node Properti can contain Variables which are expressions piii of the dependent variables the variables that hiii aoi ite i i i Tag stepl are solved for in a simulation You can define Fe global variables that can be used in several models Date created 2011 sep 14 14 44 55 Version 42a Comments Created for COMSOL a Multiphysics tutorial Parameters Functions Variables and Model Couplings 3 For the purpose of this exercise assume that you want to Introduce a second model to represent an electric device connected to the busbar through the titanium bolts A first step would be to rename Model to specify that it represents the busbar RENAMING NODES I Right click the Model I node and select Rename o gt E s Ete 7 G PT Model Builder 4 busbar mph root t Global Definitions 4 0 Modell modi Mesh Delete Rename
32. a decrease in the current density achieves this Since the current density depends on the geometry of the busbar varying the width wbb should change the current density and in turn have some impact on the operating temperature Run a parametric sweep on wbb to study this change Open the file busbar mph to add a parametric sweep to Study ADDING A PARAMETRIC SWEEP Open the file busbar mph In the l 332 Settings a o Model Builder right click Study 1 l and select Parametric Sweep 222 In the AE ES TERE hehe Settings Window click the Add button Study Settings and select the Parameter name Parameter names wbb Q 2 Entera range 5e 2 1e 2 1e 1 of Parameter values Ihis sweeps the width of the busbar from 5 cm to 0 me cm with cm increments Parameter values range Se 2 1e 2 1e 1 k Create an Average Model Coupling i Load parameter values _____ _ which you can later use to calculate Browse Read File the average temperature in the busbar Parameter Sweeps and Parallel Computing 59 3 Right click Definitions and select Model Couplings gt Average In the Settings window select All domains from the Selection list his creates an operator called aveop1 The aveop1 is now available to calculate the average of any quantity defined on those domains A little later this is used to calculate the average temperature but It can also be used to calculate average electric
33. arallel Computing 63 Parallel Computing COMSOL supports most forms of parallel computing including shared memory parallelism for example multicore processors and high performance computing HPC clusters You can use clusters to solve a series of parameter steps for a model one parameter per node or you can solve a single large model using distributed memory For maximum performance the COMSOL cluster implementation can utilize shared memory multicore processing on each node in combination with the MPl based distributed memory model This brings a major performance boost by making the most out of the computational power installed ADDING A CLUSTER COMPUTING JOB To run cluster simulations you need to enable advanced options for the Job i Configurations node Click the Show button E A s on the Model Builder and select a Model 1 modi Advanced Study Options T Model Builder amp 2 In the Model Builder under Study I 4S Study1 right click Job Configurations and LZ Step 1 Stationary gt Solver Confi tion select Cluster Computing t Tre olver Configurations Job Configurations gt Results Show Default Solver 123 25 Parametric feel Batch h Cluster Computing Ps Delete Solvers 64 Parallel Computing Se t i CO The Cluster Computing Settings window helps to manage the simulation either for running several instances of an identical parameterized
34. ating of the device The electric potential at the upper right vertical bolt surface is 20 mV and that the potential at the two horizontal surfaces of the lower bolts is Q V Thorough Example The Busbar 7 MODEL WIZARD I Open COMSOL by double clicking its icon on the desktop When the Model Wizard opens select a space dimension the default is 3D Click the Next button s 2 n the Add Physics window click the Heat Transfer gt Electromagnetic Heating folder then right click Joule Heating js and choose Add Selected You can also double click or click the Add Selected button to add the interface 3 Click the Next button 4 In the Select Study Type window click to select the Stationary study type Click the Finish button 4 Any selection from the Custom Studies branch needs manual fine tuning Preset Studies are studies that have solver and equation settings adapted to the selected physics in this example Joule heating 8 Thorough Example The Busbar YS Model Wizards m Select Space Dimension cy en 5 2D axisymmetric A 2D 6 1D axisymmetric 1D 50D 9 Model Wizard E Add Physics oo g gt I Acoustics e Chemical Species Transport gt EI Electrochemistry gt Fluid Flow Heat Transfer j Heat Transfer in Solids ht amp Heat Transfer in Fluids ht Heat Transfer in Porous Media ht i ID Bioheat Transfer ht ie Heat Transfer in Thin Shells htsh
35. awin FE Mechanics solid Right click or double click to mm add it to the Selected physics section Add Physics eo 4 p Se Chemical Species Transport n i aia pee oP b ell Electrochemistry G amp t Fluid Flow t Heat Transfer t Plasma gt at Radio Frequency a La Structural Mechanics Solid Mechanics solid Thermal Stress ts E Poroelasticity poro C Shell shell Electromechanics emi St Beam beam Bb Truss truss Joule Heating and Thermal Expans mi 4 es Stationary under Preset Studies Click the a aoa Finish button 4 Select Study Type da ch Studies a ee Preset Studies Frequency Stationa amy ry H Frequency Transient DM Frequency Domain IZ Stationary bW Time Dependent gt ae Custom Studies GEOMETRY Under Model I right click a Tig E ul ss E F F A Geometry I A and select TT Meriel Buiter call _ 4 Untitled mph root Import e Global Definitions a i Modell mod Build AIl Ea Mes S Import LiveLink Interfaces Block Cone Cylinder 78 Easy Example The Wrench 2 From the Geometry import list select COMSOL Multiphysics file 3 Click Browse and locate the file wrench mphbin in the Model Library folder COMSOL_Multiphysics Structural_Mechanics Double click to add or click Open Import Geometry import 4 Click Import to display the geometry in the Graphics window THLS
36. cle representing the position of the first bolt Click the Zoom Extents button i on the Graphics toolbar Work Plane Work Plane Plane type Face parallel hd Planar face el Origin Center of face r pee Geometry Sequences 7 1 Under Work Plane 2 right click Geometry and select Circle 0 it Settings gt D Circle In the Settings window under Size and Shape define a circle with radius rad_1 and the Center x and y coordinates 0 0 Type Object Type Click Build Selected Gq Size and Shape Radius rad_1 m Sector angle 360 deg Position Base Center Your geometry should match this figure a 12 Continue creating the bolt by adding an extrude operation In the Model Builder right click Work Plane 2 and select Extrude amp 72 Geometry Sequences 13 In the Settings window in the first row of the Distances from Work Plane table enter 2 tbb to extrude the circle a distance equal to the thickness of the busbar TT Model Builder 4 Y busbar mph root t Global Definitions 4 Modell mod b Definitions a A Geometry 1 a Work Plane 1 wp A Geometry E Rectangle 1 rl amp Rectangle 2 r2 hy Difference 1 difl r Fillet 1 Full Fillet 2 fil2 a by View 2 Es Axis RS Extrude 1 ext a Work Plane 2 wp2 gt A Geometry p bY View3 38 Form Union fin b Materials b gt Joule Heating
37. d flow only takes place in the fluid domain and then set the inlet outlet and symmetry conditions 12 n the Model Builder click the Laminar Flow node In the Settings window click the Clear Selection button 4 Laminar Flow v Interface Identifier 13 n the Graphics window click the air box domain number and right click to add tt iiaii E to the Selection just list like in Domain Selection Selection All domains t Equation 52 Adding Physics to a Model You can also verify that Air in Materials has all the properties that this multiphysics combination requires In the Model Builder under Materials click Air In the Settings Window s Material Contents list verify that there are no missing properties which are marked with a warning sign A Continue with the boundaries 14 n the Model Builder right click Laminar Flow From the context menu s boundary section select Inlet a Fria Inlet Boundary Selection T y b t Override and Contribution Equation Boundary Condition Velocity Normal inflow velocity E Velocity field Uy miss Adding Physics to a Model 53 15 In the Graphics window select the inlet boundary and right click to add it to the Selection list just like in step I6 Go back to the Inlet Settings window In the U field enter Vin to set the Normal inflow velocity Cross check Boundary 2
38. del Builder right click the Materials node and select Open Material Browser d g Material or select View gt Material Browser a 4 dE Open Material Browser gt X Joul ES Mesh E Dynamic Help 46 Adding Physics to a Model 2 In the Material Browser expand the Built In tree Right click Air and select Add Material to Model 3 Close the Material Browser 4 n the Model Builder under Materials click the Air node a amp Materials t Copper t Titanium beta 215 gt Air 5 In the Graphics window click the air box to highlight it and right click to add it to the selection list Now you can add the physics of fluid flow EE Settings Material Browser om N Material Browser Materials 4 Built In Air Aluminum 6063 T83 Aluminum 8 American red oak 8 Beryllium copper UNS C17200 Brick Cross check Domain I Gad Settings _ a a Material Geometric Entity Selection Selection 1 4 Adding Physics to a Model 47 ADDING FLUID FLOW 1 In the Model Builder right click Model I and select Add Physics 8 2 n the Model Wizard select Fluid Flow gt Single Phase Flow gt Laminar Flow then Add Physics ao g aN Recently Used amp AC DC click the Add Selected button and the Finish J Acoustics button e Chemical Species Transport A lel Electrochemistry Save the model with a ne
39. di Boundary Electromagnetic Heat Source b E Mesh 1 om Periodic Condition gt S22 Study 1 b gt Results gt Ss Et Oo Lo Joule Hea Joule Heating Model 4 Electromagnetic Heat Source Infinite Elements Initial Values Heat Transfer in Solids Electric Currents a Heat Flux Heat Tranfer in Sok Electric Currents Pairs Edges Points lete m Delet Delet Disable lt Rename F Froperties Fl Dynamic Help F1 When you right click any node in the tree a context menu displays all the available features The options in the menu include everything you need to build and document a model So you just right click for various settings like geometry physics mesh or results instead of opening separate windows Capture the Concept 5 If you choose an action that requires specification the matching Settings window displays next to the Model Builder Selected Node and its Settings Window I Model Builder 9 E S 4 busbar mph root 4 Global Definitions Pi Parameters a Model 1 mod1 gt Definitions gt A Geometry 1 gt 8 Materials gt Joule Heating jh ES Mesh 1 4 Se Study Step 1 Stationary gt Fre Solver Configurations a Results gt E Data Sets B Derived Values H Tables a Temperature jh E Surface 1 a 3D Plot Group 2 Surface 1 RE Export 1 o bei Settings fe 0 O x Joule Hea
40. dulus rows are now Material Contents i Prope Name Value available in the table The warning sign Ay n WIE MoguILS indicates the values are not yet defined POER F To define the values click the Value Feche conducinty sipna 599e column In the Bulk modulus row enter Heat capacity at const Cp 385 Sel rl ee 140e9 and in the Shear modulus row Relative permittivity epsil 1 enter 46e9 Density rho 8700 k Thermal conductivity k 400 W Relative permeability mur 1 474 zr By adding these material properties you have changed the Copper material However you cannot save this in the read only Solid Mechanics material library However you can save it to your own material library 4 n the Model Builder right click Copper and select Add Material to User Defined Library M 4 amp Materials Copper Ti User Defined Property Group J Joule Mesh J Add Material to Library User Defined Library lt Study 1 tt Move Down Ctrl Down ben Rec Material Properties and Libraries 35 5 Right click Materials and select Open Material Browser In the Material Browser right click User Defined Library J and select Rename Selected Enter My Materials in the Enter New Name dialog box Materials 988 Recent Materials t W Material Library gt Built In pb AC DC gt na Batteries and Fuel Cells b Liquids and Gases t w MEMS Piezoelectric b
41. dy 2 Save the model 8 Right click the Study I node and select Compute to solve the problem When adding study steps you need to manually connect the correct physics with the correct study step Start by removing the structural analysis from the a 23 Study1 Z Step 1 Stationary Z Step 2 Stationary 1 gt fF Solver Configurations Z Stationary t Study Settings t Results While Solving Mesh Selection Physics Selection Physics interface Use Discretization Joule Heating yi Solid Mechanics x Physics settings Physics settings 4 f Study1 Step 1 Stationary IZ Step 2 Stationary 1 gt fF Solver Configurations a ee i Stationary t Study Settings Results While Solving t Mesh Selection Physics Selection Discretization Physics settings Physics settings Physics interface Use Joule Heating x Solid Mechanics yf o Compute Update Solution Parametric Sweep Study Steps Pa Show Default Solver Adding Physics to a Model 43 RESULTING DEFORMATION Under Results gt Plot Group 2 click the Surface node In the Settings window click the Replace Expression button amp and from the context menu select Solid Mechanics gt Displacement gt Total P a Displacements You can also enter solid disp in the Expression field Expression Click to clear the Manual color range check NERA box if it is selected solid disp
42. e Joule heating effect to the thermal expansion of the busbar Next fix the busbar at the position of the titanium bolts t Override and Contribution Equation Show equation assuming Study 1 Stationary 5 5o C E Eg Einells Eine ALT T ref Model Inputs IE Temperature User defined 6 In the Model Builder right click the Solid Mechanics node and select gt E Mesh1 Fixed Constraint gt sae Study 1 a Results i Data Sets Linear Elastic Material Model Hyperelastic Material Model Viscoelastic Material Model E Cam Clay Material Model Body Load Initial Values gt F F Mon B ore Reports G Free Fixed Constraint Prescribed Displacement Se ee eS eee Adding Physics to a Model 4 7 Click the Fixed Constraint node In the Graphics window rotate the busbar to view the back Click one of the bolts to highlight it and right click to add the bolt to the Selection list Cross check Boundaries 8 15 and 43 8 Repeat this procedure for the remaining bolts You can now update the Study to take the added effects into account RUNNING A STUDY SEQUENCE JOULE HEATING AND THERMAL EXPANSION The Joule heating effect is independent of the stresses and strains in the busbar assuming small deformations and ignoring the effects of electric contact pressure This means that you can run the simulation us
43. ects to the gt Work Plane 2 BS Extrude geometry sequence gt js Work Plane 3 Ra Extrude 3 Form Union In the next set of steps you will create a profile of the busbar Geometry Sequences 67 3 In the Model Builder Under Work Plane I sok T E y Gl A right click Geometry and select Ti Rectangle m Under Size enter L 2 tbb in Rectangle Click the Build Selected button Type v Size Width L 2 tbb m Height 0 1 m Position 4 Create a second rectangle Under Work Plane 1 right click Geometry A and select Rectangle m Enter L tbb in the Width field it Settings Rectangle 0 1 tbb in the Height field and tbb in the y eee position field Type Click the Build Selected button O Size Use the Boolean Difference operation to Width L tbb m subtract the second rectangle from the first Height 0 1 tbb m one Position x o m y tbb m 5 Under Work Plane I right click Geometry and select Boolean Operations gt Difference H kad Settings In the Graphics Window click r1 and t Difference right click to add r1 to the Objects to add list isa Click the Activate selection button y in the Objects to add Objects to subtract list then right click to add rl 0 r2 to the Objects to subtract list Click Build Selected You should now have a backward facing L shaped profile Continue by rounding the corners using fillets Objects to subtract 1 c 68 Geometry
44. eering Module Subsurface Flow Module Heat Transfer Module and Microfluidics Module The Electric Currents interface solves for the electric potential in applications where electric currents flow in a conductive media The Heat Transfer in Solids interface provides default settings for conductive heat transfer in solids But you can easily switch from heat transfer in solids to heat transfer in fluids as well as add and combine different heat transfer mechanism within the same Heat Transfer interface The Heat Transfer in Fluids interface provides default settings for convective and conductive heat transfer in fluids But you can easily switch from heat transfer in fluids to heat transfer in solids as well as add and combine different heat transfer mechanism within the same Heat Transfer interface In 2D models you can switch between plane stress and plane strain without adding a new physics interface The Deformed Geometry interface Is available for all geometries not just 2D In version 4 it is also possible to study fully parameterized geometries using parametric sweeps New Terminology in Version 4 95 Material Libraries NEW NAME Built in MEMS Piezoelectric AC DC Convective Cooling boundary condition Liquids and Gases Material Library Batteries and Fuel Cells NAMES IN 3 5A Basic Material Properties MEMS Material Properties Piezoelectric Material Properties Electric AC DC Material P
45. er L 2 1 5e 2 in the ire x field and wbb 4 in the y field 15 Size and Shape Click Build Selected Radius rad_1 m Sector angle g Copy the circle that you just created to NER cs generate the third bolt in the busbar v Position Ey nn Rotation Angle 74 Geometry Sequences 16 Under Work Plane 3 right click Geometry A la a and select Transforms gt Co a la Copy In the Graphics window click the circle c1 to highlight it Right click anywhere in the sai Graphics window and add the circle to the pii Input object list in the Settings window a T Under Displacement enter wbb 2 in the y i field Click Build Selected Fj Keep input objects Displacement x 0 iT edl yi wbb 2 m m Your geometry should match this figure gt Continue by extruding the circles 7 In the Model Builder right click Work Plane 3 amp and select Extrude amp In the Settings window in the first row of the Distances from Work Plane table enter 2 tbb Click Build Geometry Sequences 75 Selected jj he geometry and Its corresponding geometry sequence should match the figure Click the Save button and name the model busbar mph A Geometry 1 a js Work Plane 1 wp 4 A Geometry m Rectangle 1 fri m Rectangle 2 r2 oy Difference 1 fdifi i Fillet 1 fit Fillet 2 fil2 p Lx View 2 BS Extrude 1 fexti a js Work Plane 2 wp2 A Geometry Circle 1 fcl p bx View 3 RS Extrude 2 ext2
46. et boundary boundary number 2 and right click to add it to the Selection list in the Settings window This sets the inlet temperature to 293 K the default setting Continue with the outlet Cross check Boundary 2 10 n the Model Builder right click Joule Heating gt In the second section of the context menu select Heat Transfer in Solids gt Outflow L I Joule Heating Model L I eos Electromagnetic Heat Source Infinite Elernents l i a Initial Values ar J i Fu I Heat Transfer in Solids Electric Currents oo ad a Boundary Electromagnetic Heat Source oe Periodic Condition Ti Heat Transfer in Solids Temperature KA ED Mes Electric Currents t oa Thermal Insulation gt ga Study 1 i es gt Results Pairs a Outflow Edges t Symmetry k RA E r Adding Physics to a Model 5 11 In the Graphics window click the outlet boundary boundary number 5 and right click to add it to the Selection list in the Settings window Cross check Boundary 5 The settings for the busbar bolts and for the Electric Potential I and Ground I boundaries have retained the correct selection even though you added the box geometry for the air domain To see this click Electric Potential and then Ground I in the Model Builder to verify that they have the correct boundary selection Continue with the flow settings You need to indicate that flui
47. fter completing the Joule heating simulation you now know that there is temperature rise in the busbar So it is logical to ask What kind of mechanical stress is induced by thermal expansion To answer this question COMSOL Multiphysics makes It easy for you to expand your model to include the physics associated with structural mechanics If you are more interested in adding cooling by fluid flow you can skip to the section Fluid Flow on page 45 ADDING SOLID MECHANICS The Structural Mechanics Module which enhances the Solid Mechanics interface is required to complete these steps 1 Open the model busbar mph that was created earlier In the Model Builder right click the Busbar 4 Busbar modi Definite i Add Physics y A Geomet ey wt WWateria ea M node and select Add Physics 8 esh Adding Physics to a Model 39 2 In the Model Wizard select Structural 7 _ Mechanics gt Solid Mechanics To add this YF Model Wizard e o node you can double click it right click Add Physics es and select Add Selected or click the Add Selected button S88 Chemical Species Transport gt El Electrochemistry gt Fluid Flow 3 Click the Finish button 4 and save the gt Heat Transfer J model with a new name busbar_II mph v O Pia gt Ea Radio Frequency a Structural Mechanics Solid Mechanics solid 5 Thermal Stress ts l E Poroelasticity poro C Shell shell a Electr
48. greement COMSOL COMSOL Desktop COMSOL Multiphysics Capture the Concept and LiveLink are registered trademarks or trademarks of COMSOL AB AutoCAD and Inventor are registered trademarks of Autodesk Inc in the USA and other countries LiveLink for AutoCAD and LiveLink for Inventor are not affiliated with endorsed by sponsored by or supported by Autodesk Inc and or its affiliates and or subsidiaries MATLAB is a registered trademark of The Mathworks Inc Pro ENGINEER is a registered trademark of Parametric Technology Corporation or its subsidiaries in the U S and in other countries SolidWorks is a registered trademark of Dassault Systemes SolidWorks Corp SpaceClaim is a registered trademark of Space Claim Corporation Other product or brand names are trademarks or registered trademarks of their respective holders Version Part No CM010004 October 2011 COMSOL 4 2a Contents OOUE Oaa e a erat cree ie ener eee are Capre CON ODE reagia tore eaten tect 3 MOFOUCR Exampie Tne DUSO di esio Sl sce ete a 7 Parameters Functions Variables and Model COURIC ra a E pa eee eee ae 29 Material Properties and Libraries n a naana auaa 34 Mesmo ocguU nC s 4 vat det aeons a a e paT oy Addie Fooie toa MOC eat ieser ae oan ee aa tes 39 Parameter Sweeps and Parallel Computing 60 Paralel CORDON s ei ren a a N 65 SONS te SCO N OE Aca Varese ere weit hear 6 Easy Example ine VV CCA CM adi g sana asi hearts ae ese 78
49. hich turns the boundary red and right click to select it which turns the boundary blue 3 Click the Go to Default 3D View button to restore the earlier view Cross check Boundary 35 4 Click the Zoom Box button to prepare the view shown in 5 n the Model Builder right click Solid Mechanics solid and gt gt Linear E select Boundary Load gt S22 Study 1 b Results Linear Elastic Material Model 3 Hyperelastic Material Model Viscoelastic Material Model J Carm Clay Material Model Body Load 3 Initial Values More Free Fixed Constraint Prescribed Displacement Prescribed Velocity Prescribed Acceleration Symmetry Antisymmetry Roller 82 Easy Example The Wrench Thin Film Damping ay i fa fa fa ay fam fa A f iat ry fa oat a Boundary Load p er 1 a d T c i on d it T on 6 Rotate the geometry by left clicking and dragging it into the position shown Then select the top socket face by left clicking to highlight the boundary and right clicking it to add it to the list O Cross check Boundary 1 7 n the Boundary Load Settings window under Force select Total force as the Load type Load type and enter F he negative sign Indicates the negative z direction Total force w i Because the geometry contains small edges and faces reduce the size of the Force downward MESH min
50. ilder Move to the next selected node in the Model Builder Select all domains boundaries edges or points select all cells in a table Copy text in fields Paste copied text Undo the last operation Redo the last undone operation Move a physics node except default nodes material node mesh node study step node or results node up one step Move a physics node except default nodes material node mesh node study step node or results node down one step Switch focus to the next window on the desktop Switch focus to the previous window on the desktop Switch focus to the Model Builder window Switch focus to the Settings window Switch focus to the previous section in the Settings window Switch focus to the next section in the Settings window Open context menu Open list of predefined quantities for insertion in Expression fields for plotting and results evaluation Keyboard Shortcuts 93 New Terminology in Version 4 The following tables include new terminology and names in version 4 and the corresponding equivalents in version 3 5a General Terminology NEW NAME Parameters Variables Physics interface Coupling operators Hide Study type Results branch Convert to Domain Bidirectional symmetric constraint Unidirectional constraint NAME IN 3 5A Constants Expressions Expression variables Application mode Coupling variables Suppress Analysis type Po
51. ility in physics but it is the new user interface that stands out the most Organize The COMSOL Desktop helps you organize your simulation by presenting a clear overview of your model at any point It uses functional form structure and aesthetics as the means to achieve simplicity for modeling complex realities For instance task specific tools appear on the Desktop right when you need them showing only What is currently possible which removes uncertainty from model building and brings order to your simulations The Desktop is made up of several windows which may or may not be displayed depending on the need These windows include the Model Builder Settings Graphics Messages Progress Help and others Main Menu Main Toolbar Settings Window Graphics Window F r fale Dp Hepo 08868 se 0U i Hirini s BSB TB Fe Ty Mosel sider de ET Ts tartan S gh Gane Aa AE ia a ke FE a m E eee T Surtace E Modal jma Dra B Dimi kT ete ot Fom presi a elaine A Greate Taperne amp TR iepr 1 ie Nica Par 1 Jap 1 Epen e 1 gA Foen tes fir Unt Heh a Despair Hea Mire ag Pa Ham Timir on bah Empor a Thama hidon 1 a ti iia rasai Veer 1 J imdi b Tis k oasi eee a Tmerre Toksika d ph a heia j Dais beneg Sater jabia G Hori Coix iaie ieee apps me ees Mate F Tein begi w Seke Demirpa toea prena com bbir D Manat TETERA sober nergy F Gas r Dhartved ehats W Tia fy om he tia i Empr era et 2
52. ime and displays the default von Mises stress in a Surface plot with the displacement visualized using a Deformation subnode Change to a more suitable unit as follows In the Model Builder expand the Results gt Stress solid node then click Surface 1 m 2 Go to the Settings window for Surface 3 Locate the Expression section From the Unit list select MPa 4 Click the Plot button 84 Easy Example The Wrench 5 Click the Zoom Extents button on the Graphics toolbar COISSI n AULTIPHHSI ECS YF 0 1718 von Mises stress distribution in bolt and wrench under an applied vertical load Next we are going to determine the location of greatest tension by plotting the principal stress field s PLOTTING THE PRINCIPAL STRESS FIELD I Right click the Results node and add a 3D Plot Group G gt 4B 30 Plot Group 2D Plot Group b E 1D Plot Group iE 3 Polar Plot Group w Plot All Easy Example The Wrench 85 2 Right click the 3D Plot Group node i and select Contour 3 gt ie 3D Plot Grou ell Export wi Plot Reports Plot In i Volume E Arrow Volume t Surface i Slice i Isosurface E Arrow Surface Line Contour J co _ re 3 In the corresponding Contour Settings window click the Replace Expression button amp and select Solid Mechanics gt Stress gt Principal stresses gt First principal stress solid sp1 which is representative of the
53. imum element In the Model Builder click Model 1 gt Mesh I amp 2 Go to the Settings window for Mesh 3 Locate the Mesh Settings section From the Sequence type list select User controlled mesh 4 Click Model I gt Mesh I gt Size 43 5 Go to the Settings window for Size 6 Locate the Element Size section Click the Custom button 7 Locate the Element Size Parameters section In the Minimum element size edit field enter 0 0012 Click the Build All button oe Easy Example The Wrench 83 STUDY The following steps are needed to set up an Iterative solver By using such a solver you can significantly reduce the memory amount needed for the calculations If your computer has more than 2 GB of memory you can skip these steps and go directly to step 6 to compute the solution In the Model Builder right click Study and choose Show Default Solver y Expand the Study I gt Solver Configurations gt Solver I gt node Right click Stationary Solver I and choose Iterative P Right click Iterative I and choose Multigrid fee Right click Study and select Compute 4 Sa Study Z Step 1 Stationary 4 fp Solver Configurations F Solver 1 aud Compile Equations Stationary gt WWW Dependent Variables 1 4 z Stationary Solver 1 Direct i Advanced m Fully Coupled 1 a fs Iterative 1 Incomplete LU gt Multigrid 1 DISPLAYING RESULTS COMSOL finishes after about one minute of computation t
54. inclusive modeling environment COMSOL gives you the confidence to build the model you want with real world precision Certain characteristics of COMSOL become apparent with use Compatibility stands out among these COMSOL requires that every type of simulation included in the package has the ability to be combined with any other This strict requirement actually mirrors what happens in the real world For instance in nature electricity is always accompanied by some thermal effect the two are fully compatible Enforcing compatibility guarantees consistent multiphysics models and the knowledge that even as the COMSOL family of products expands you never have to worry about creating a disconnected model again Another noticeable trait of the COMSOL platform is adaptability As your modeling needs change so does the software If you find yourself in need of including another physical effect you can just add it If one of the inputs to your model requires a formula you can just enter it Using tools like parameterized geometry interactive meshing and custom solver sequences you can quickly adapt to the ebbs and flows of your requirements Introduction COMSOL Multiphysics also has several problem solving benefits When starting a new project using COMSOL helps you understand your problem You are able to test out various geometrical and physical characteristics of your model so you can really hone in on the important design challenges
55. ing the temperature as input to the structural analysis In other words the extended multiphysics problem is weakly coupled As such you can solve it in two separate study steps one for the strongly coupled Joule heating problem and a second one for the structural analysis In the Model Builder right click Study I 2 and select Study Steps gt Stationary to add a second stationary study step T Model Builder gt o H s Et i 7 4 aw busbar mph root b Global Definitions r uv Model 1 mod t Definitions gt A Geometry 1 gt 8 Materials b Joule Heating jh gt E Mesh1 i je Stud j t Compute gt MS Update Solution F5 ok c Til Parametric Sweep Study Steps Fite Stationary ty Fes Show Default Solver MQ Time Dependent iit Ergenfrequency Rename F2 t EE S 42 Adding Physics to a Model first step 2 Under Study I click the Step I Stationary node j 3 In the Settings window under Physics Selection click the Solid mechanics solid row in the Physics interface table 4 n the Use column click to change the check mark to an to remove Solid mechanics from Study I Then remove Joule heating from the second step 5 Under Study I click Step 2 Stationary 6 In the Settings window under Physics Selection click the Joule heating jh row in the Physics interface table 7 In the Use column click to change the check mark to an to remove Joule Heating from Stu
56. jh gt Ea Mesh 1 gt 22 Study 1 b gt Results Click the Build Selected button amp the cylindrical part of the titanium bolt that runs through the busbar Draw the two remaining bolts ci T beil Set iE amp Extrude General Input objects Keep input objects Keep cross sectional faces Distances from Work Plane Distances rm 2 tbb t Scales Displacements t Twist Angles t Polygon Resolution of Edges Selections of Resulting Entities Create celertinngc to create Geometry Sequences 73 14 Right click Geometry I A under Model 1 and select Work Plane amp A Work Plane 3 node is added In the Settings window for Work Plane 3 select Face parallel as the Plane type In the Graphics window click face 4 shown in the figure When this surface is highlighted red right click anywhere in the Graphics window to add it to the Planar face list in the Settings window Face number 4 is now highlighted blue Click the Show Work Plane button and the Zoom Extents button k to get a better view of Face 4 the geometry To parameterize the position of the two remaining bolts add the circles that form the cross sections of the bolts 15 Under Work Plane 3 right click Geometry 58 Settings HEr Gais and select Circle i D Circle In the Settings window under Size and Shape enter rad_1 in the Radius field iia tata Under Position ent
57. model one parameter value per host or for running one parameter step in distributed mode You choose which type of cluster job you want to do from the Cluster type ist COMSOL supports Windows Compute Cluster Server 2003 Windows HPC Server 2008 and Linux To learn more about running COMSOL in parallel see the Installation and Operations Guide 34 Settings i Cluster Computing General gla A Defined by study step User defined Frepend command Postpend command Batch job Custer Settings Cluster type Number of nodes Node granularity Exclusive nodes Advanced Scheduler Requested nodes Cores per node Memory per node MB Runtime minutes User Priority HPCs 2008 al 50 localhost 0 0 Infinite Normal r Parallel Computing 65 Geometry Sequences This section details how to create the busbar geometry using COMSOLs geometry tools The step by step instructions take you through the construction of the geometry using parameters set up in Global Definitions Using parameterized dimensions helps to produce what if analyses and automatic geometric parametric sweeps If you have not yet done so follow the steps under the Model Wizard and Global Definitions starting with Thorough Example The Busbar on page 7 Then return to this section to learn about geometry modeling The first step in the geometry sequence is to draw the profile of the busba
58. nstructions describe the essential components of the model building procedure highlighting several features and demonstrating the common simulation tasks At the end you will have built a truly multiphysics model The model that you are about to create analyzes a busbar designed to conduct direct current to an electric device see below The current conducted in the busbar from bolt to bolts 2a and 2b produces heat due to the resistive losses a phenomenon referred to as Joule heating The busbar is made of copper while the bolts are made of a titanium alloy The choice of materials is important because titanium has a lower electrical conductivity than copper and will be subjected to a higher current density Titanium Bolt 2a Titanium Bolt 2b Titanium Bolt The goal of your simulation is to precisely calculate how much the busbar heats up Once you have captured the basic multiphysics phenomena you will have the chance to investigate thermal expansion yielding structural stresses and strains in the busbar and the effects of cooling by an air stream The Joule heating effect is described by conservation laws for electric current and energy Once solved for the two conservation laws give the temperature and electric field respectively All surfaces except the bolt contact surfaces are cooled by natural convection in the air surrounding the busbar You can assume that the bolt cross section boundaries do not contribute to cooling or he
59. omechanics emi Ert Beam beam Bb Truss truss Joule Heating and Thermal Expans m When adding additional physics interfaces you need to make sure that materials included in the Materials node have all the required properties for the selected physics interfaces In this example you already know that all properties are available for copper and titanium You can start by adding the effect of thermal expansion to the structural analysis 4 n the Model Builder under Solid Mechanics 4 S Joule Heating Gh right click the Linear Elastic Material Model Joule Heating Model 1 node and select Thermal Expansion Ha are a Boundary Electromagnetic Heat Source 1 A Electric Insulation 1 A Thermal Insulation 1 3 Initial Values 1 A Heat Flux 1 A Electric Potential 1 ew Ground 1 a E Solid Mechanics solid a EO Linear Elastic Material Model 1 I Thermal Expansion 1 a Freel EJ Initial Values 1 T D T T T With the Structural Mechanics Module the Thermal Stress predefined multiphysics interface is also available to define thermal stresses and strains 40 Adding Physics to a Model 5 On the Thermal Expansion Settings oo Setti i window under Model Inputs select uih Temperature jh jhl from the Thermal Expansion Temperature list Domain Selection This is the temperature field from the Selection All domains Joule Heating interface jh jhml and couples th
60. on with a single example gp1 argument within parenthesis For The Gaussian pulse function defines a example bell shaped curve according to the gp1 x expression s So 1 20 y s e oV2n It is defined by the mean parameter So and the standard deviation o The function has one argument 90 Supported External File Formats FUNCTION Interpolation Piecewise Ramp Random Rectangle ARGUMENTS AND DEFINITION The function name is its identifier for example int1 An interpolation function is defined by a table or file containing the values of the function in discrete points The file formats are the following spreadsheet grid or sectionwise The function has one to three arguments The function name is tts identifier for example pw A piecewise function is created by splicing together several functions each defined on one interval Define the argument extrapolation and smoothing methods and the functions and their intervals This function has one argument with different definitions on different intervals which must not overlap or have any holes between them The function name is its identifier for example rm1 A ramp function is a linear increase with a user defined slope that begins at some specified time The function has one argument It can also be smoothed The function name is its identifier for example rn A random function generates white noise with uniform o
61. onjugate Heat Transfer j Multiphysics interface is available This automatically defines coupled heat transfer in solids and fluids including laminar or turbulent flow Adding fluid flow to the Joule heating model forms a new multiphysics coupling To simulate the flow domain you need to create an air box around the busbar You can do this manually by altering the geometry from your first model Alternatively you can load a file including the geometry and the solution to the Joule heating problem To load the geometry select View gt Model Library IH browse to COMSOL Multiphysics gt Multiphysics gt busbar_box and click Open Having loaded or created the geometry now simulate the air flow as in this figure Air Outlet Start by adding a new parameter for the inlet flow velocity Adding Physics to a Model 45 DEFINING INLET VELOCITY Under Global Definitions click the a Parameters node Pi 4 Global Definitions Pi Parameters 2 In the Settings window click the last row In the Parameters table Enter Vin in the Name i Settings z column and 1e 1 m s in the Expression P Parameters column Enter a description of your choice 5 cae The next step is to add the material eats T properties of air 5 mm 0 005 m 5 cm 0 05 im 6 mm 0 006 m 5 Wim 2 K 5 W m _ 20 mV 0 02v le 1 m s 0 1 ms Expression 1e 1 m s Description Inlet velocity ADDING AIR In the Mo
62. oring the solution progress For instance you can follow the solution in a critical point during a time dependent simulation or at parameter value in a parametric study You can also use Model Couplings to map variables from one face in a model to another extrusion couplings or to integrate a variable along curves and map from one entity to another projection couplings You can find an example of using the average operator in Parameter Sweeps and Parallel Computing on page 59 Also see Built in Functions on page 90 for a list of available COMSOL functions To learn more about working with definitions in the Model Builder click the Definitions or Global Definitions node and press F to open the Dynamic Help window f This window displays help about the selected item in the COMSOL Desktop and provides links to the documentation You can also open it from the Help menu It could take up to a minute for the window to load the first time it is activated but the next time it will load quickly Parameters Functions Variables and Model Couplings 33 Material Properties and Libraries Up to now you have used the functionality in Materials to access the properties of copper and titanium in the busbar model In this section you define material properties and create your own material library In Materials you are also able to create your own materials and save them in your own material library You can also add material pro
63. orrect physics with the correct study step Start by removing Joule heating from the first step 56 Adding Physics to a Model 2 Under Study I click Step I Stationary In the Settings window under Physics Selection click the Joule heating jh row in the Physics interface table In the Use column click to change the check mark to an 3 to remove Joule heating from Study Remove the fluid flow from the second step 4 Under Study I click Step 2 Stationary I i In the Settings window under Physics Selection click the Laminar flow spf row in the Physics interface table In the Use column click to change the check mark to an to remove Laminar flow from Study 2 Press Ctrl S to save the model Right click Solver Configurations and select Delete Solvers to clear any solver settings that may be kept from the last solution se 4 i rai a ey Study 1 Z Step 1 Stationary Step 2 Stationary 1 gt fF Solver Configurations G Physics Selection Discretization Physics interface Joule Heating jh Laminar Flow spf Physics settings F F Physics settings Physics Selection Physics interface Discretization Joule Heating jh Laminar Flow spf Physics settings F Physics settings F amp Study 1 Z Step 1 Stationary Solver Configurations Results fp Show Default Solver gt HE Data 8 Der A Clear Solutions H Tabl fx Delete Solver
64. oung s modulus E 110e9 Pa Pa Young s modulus and P Poisson s ratio nu 0 35 1 Young s modulus and P Me ee ee Ll 1 TIa 8lakew The Material Contents section has useful feedback about the model s material property usage Properties that are both required by the physics and available from the material are marked with a green check mark w Properties required by the physics but missing in the material result in an error and are marked with a warning sign A A property that is available but not used in the model is unmarked The Coefficient of thermal expansion property is not used but it is needed later when heat induced stresses and strains are added to the model Because the copper material is added first by default all parts have copper material assigned In the next step you will assign titanium properties to the bolts which overrides the copper material assignment for those parts 4 Thorough Example The Busbar 7 In the Model Builder click Titanium beta 2 1S 4 09 busbar mph root 8 Select All Domains from the Selection list and then click b Global Definitions domain 1 Click the Remove from Selection button cance b Definitions b gt A Geometry 1 a amp Materials gt 8 Copper t 8 Titanium beta 215 b Joule Heating jh Material Geometric Entity Selection Geometric entity level Dor Selection 8 Cross check Domains 2 3 4 5 6 and 7 Thorough Example The Busbar 5
65. perties to existing materials In cases where you define properties that are functions of other variables typically temperature the plot functionality helps you to verify the property functions in the range of interest First investigate how to add a property to an existing material Assume that you want to add bulk modulus and shear modulus to the copper properties Locate and open the file busbar mph if it is not already open on the COMSOL Desktop CUSTOMIZING MATERIALS In the Model Builder under Materials click Copper amp 4 busbar mph root Global Definitions 4 4 Modell modi Definitions gt A Geometry 1 a 8 Materials gt Copper gt Titanium beta 215 V Joule Heating jh amp B Mesh 1 2 In the Settings window the Materials PR Properties section contains a list of all the gt Basic Properties definable properties Expand the Solid gt Gas Models Mechanics gt Linear Elastic Material Model node A A a acelai Rj h f 4 Linear Elastic Material Model lont click Bulk Modulus and Shear Modulus ee Ralio and select Add to Material gt Lam Constants mee e e ee Euk modulus and Shear Mode Is lets you define the bulk modulus an shear modulus for the copper in your model gt Pressure Wave and Shear Wave Speeds gt Orthotropic Anisotropic 34 Material Properties and Libraries 3 Locate the Material Contents section Bulk modulus and Shear mo
66. potential current density and so forth 4 Right click Study I and select Compute to run the sweep Save the model as busbar _III mph The results show the temperature in the busbar 08 Settings go Average Operator Name Operator name aveopl Source Selection All domains Selection 1 2 3 4 5 6 T a for the last parameter value wob 0 cm Compare this to the temperature for wbb 5 cm 5 In the Model Builder click the first Temperature node In the 3D Plot Group Settings window select Solution 2 ij from the Data set list This data set contains the results from the parametric sweep Data Data set 6 In the Parameters value list select Gea Settings gt 3D Plot Group Parameter value wbb 0 05 Click the Plot button Plot Settings View Autor i 09 Tithe E Sur Plot data set edges Frame 60 Parameter Sweeps and Parallel Computing r Material x y z ka 7 Under the first Temperature node click the Surface node M In the Settings window click Range and select the Manual color range box Enter 323 in the Maximum field 309 35 for the 10 cm case wbb 1 0 05 Surface Temperature K A 330 75 330 329 328 327 326 325 w 0 1 324 10745 323 W 322 72 wbb 6 0 1 Surface Temperature kK 317 71 sl 316 a13 314 3l3 312 311 310 ae 309 22 The maximum temperature decreases from 33
67. r 1 Right click Geometry I A and select Work Plane In the Settings window select xz plane from the Plane list Click the Show Work Plane button on the Settings toolbar Continue editing the axis and grid settings in Work Plane I 66 Geometry Sequences F Settings ECEE amp Work Plane Work Plane Plane type Plane y coordinate mi 3D projection Entire 3D geometry Selections of Resulting Entities Create selections L and click Axis t Enter the values for the 2 In the Model Builder expand the View 2 node oats C x and y minimums and maximums see the it Settings gt figure into the Axis fields and the x and y Dx Axis spacing in the Grid fields Select the Manual Axis Spacing check box ere ea Leave the Extra x and Extra y fields blank xmaximum 0 11 Click the Apply button y minimum le 2 y maximum 011 Preserve aspect ratio Grid Manual spacing xspacingi 5e 3 y spacing 5e 3 Extra x Extra y tt Geometry Toolbar You can use interactive gegt s id e 4 ryYwvOes drawing to create a geometry H T Model Builder gt S S Et E 7 o f Settings using the drawing toolbar 4 W busbar mph i eee eres A Geometry SERS le pola and a Model1 clicking in the Graphics gt Definitions ee window You can also a amp Work Plane1 right click the Geometry node VA Geometry l oa y A under Work Plane I to S Extrude 1 add geometric obj
68. r normal distribution and has one or more arguments to simulate white noise The function has arbitrary number of arguments The function name is tts identifier for example rect A rectangle function is 1 in an interval and O everywhere else The function has one argument CALL The name of the function with comma separated arguments within parenthesis For example int1 x y Z The name of the function with a single argument within parenthesis For example pw x The name of the function with a single argument within parenthesis For example rmi x The name of the function with comma separated arguments within parenthesis For example rni x y The arguments x and y are used as a random seeds for the random function The name of the function with a single argument within parenthesis For example rect1 x Supported External File Formats 9 ARGUMENTS AND DEFINITION FUNCTION The name of the function with a single Step Triangle Waveform also be smoothed The function name is its identifier for example step A step function is a sharp transition from O to some other value amplitude at some location The function has one argument It can also be smoothed The function name is tts identifier for example tri A triangle function is a linear increase and linear decline within an interval and O everywhere else The function has one argument It can also be smoothed
69. red and right click to add itto the Cross check Domain I Selection list which changes the color to blue Adding Physics to a Model 49 Now couple fluid flow with heat transfer Bi setings _ o S Heat Transfer in Fluids Inthe Settings window under Model Inputs select Velocity field spf fp1 from the Velocity field list This identifies the flow field from the a Laminar Flow interface and couples it to Domain Selection Selection heat transfer t Override and Contribution Equation Model Inputs Temperature T Temperature jh jh Absolute pressure User defined 1 atrmn Pa Velocity field p C User defined Moving on to the boundary conditions specify the inlet and outlet for the heat transfer in the fluid domain 8 In the Model Builder right click Joule Heating In the second section of the context menu the boundary section select Heat Transfer in Solids gt Temperature 9 Joule Heating Model k Ele Electromagnetic Heat Source D ee Bou Infinite Elements p Ele D 2 The Initial Values OD Initi Heat Transfer in Solids A Hea Electric Currents A Ele a Gro Boundary Electromagnetic Heat Source E3 Hea Periodic Condition p E Mesh1 Heat Transfer in Solids a Temperature gt lt Study 1 ee a Thermall re Electric Currents A Thermal Insulation fim Results s sp 50 Adding Physics to a Model 9 In the Graphics window click the inl
70. ron Concrete Conner i 8 d Add Material to Model gE ai Remove Selected ae Hi h strength alloy steel g gt oy 8 Iron Magnesium AZ31B 3 Click the Material Browser tab and scroll to Titanium beta 21S in the Built In material folder 28 Settings gt Material Browser EL O Right click to Add material to model Material Thorough Example The Busbar 3 4 n the Model Builder collapse the Geometry I node A to get an overview of the model Si gsm cae hay gt Global Definitions a i Modell mod1 gt Definitions gt A Geometry 1 a Materials gt SB Copper Titanium beta 2715 gt Joule Heating jh EB Mesh1 gt amp Study 1 gt Results 5 Under the Materials node click Copper PE busbar mph root E Global Definitions 4 4 Modell modi gt Definitions gt A Geometry 1 a 8 Materials GE Ecom l gt amp 8 Titanium beta 215 6 In the Settings window examine the Material gt S Joule Heating jh Contents section gt 6B Mesh 1 Material Contents Property Name Value Unit Property group Electrical conductivity sigma 5 998 e7 5 m 5m Basic f Heat capacity at constant pr Cp 385 J kg k J kg Basic Relative permittivity epsilonr 1 1 Basic Density rho B700 kg m 3 kg Basic Thermal conductivity k 400 Wiitrm K Wia Basic Relative permeability mur 1 1 Basic Coefficient of thermal expa alpha 17e 6 1 K 1 K Basic Y
71. roperties Heat Transfer Coefficients Liquids and Gases Material Library N A 96 New Terminology in Version 4 COMMENTS Included in COMSOL Multiphysics Included with the MEMS Module Acoustics Module and Structural Mechanics Module Included with the MEMS Module Acoustics Module and Structural Mechanics Module Included with the AC DC Module The Samarium Cobalt material is no longer included In version 4 1 the Convective Cooling boundary condition replaces the library of heat transfer coefficients The Settings window for the Convective Cooling node contains predefined heat transfer coefficients for natural and forced convection both internal and external Included with the Heat Transfer Module Included with the Chemical Reaction Engineering Module Acoustics Module Subsurface Flow Module Heat Transfer Module and MEMS Module The COMSOL Material Library add on is unchanged New material library available with the Batteries amp Fuel Cells Module NH COMSOL www comsol com CMO 10004
72. s gt Tem 3D PB Z Dynamic Help c Right click the Study I node and select Compute to automatically create a new solver sequence that solves the two problems in sequence The simulation takes a few minutes to run 7 After the solution is complete click the Transparency button Compute Update Solution Parametric Sweep Study Steps Show Default Solver Pre on the Graphics toolbar to visualize the temperature field inside the box Adding Physics to a Model 57 The Temperature Surface plot shows the temperature in the busbar and in the surrounding box You can also see that the temperature field is not smooth due to the relatively coarse mesh A good strategy to get a smoother solution would be to refine the mesh to estimate the accuracy File Ede View Option Help 0298 se 08 2 y vi enha 88EDSEFe T Model iijar T S TIN O ng LS ch Gephice a Wi bathar bor Lmph jot fee Surface Data a a a Hj e eFC DJ Mirigi H E Progres Leg haria of degron of Freedom pied fom Tiii Humber of degepri of froede icheed for TAIE Humber of degree of freedom scheed fox 1TA Bi ah Fat mii 58 Adding Physics to a Model Parameter Sweeps and Parallel Computing Sweeping a Geometric Parameter Often it is interesting to generate multiple instances of a design to meet specific constraints For the busbar a design goal might be to lower the operating temperature and
73. s the capability to read and write a wide array of file formats The list below contains several formats that are compatible with COMSOL These formats are categorized according to the associated type of software MCAD FILE FORMAT READ WRITE AutoCAD dwg 3D only Yes Yes Autodesk Inventor ipt iam Yes Yes Creo Parametric prt asm Yes Yes Pro ENGINEER prt asm Yes Yes SolidWorks sldprt sldasm Yes Yes SpaceClaim scdoc Yes Yes DXF dxf 2D only Yes Yes Parasolid x_t xmt_txt x_b xmt_bin Yes Yes ACIS sat sab Yes No Step STEP Yes No IGES IGES Yes No CATIA V5 CAT Part CATProduct Yes No VRML vl Gvrml evel Yes No STL stl Yes No Requires LiveLink for AutoCAD Requires one of the LiveLink products for AutoCAD Creo Parametric Inventor Pro ENGINEER SolidVVorks or SpaceClaim or the CAD Import Module Requires LiveLink for Creo Parametric Requires LiveLink for SpaceClaim Requires the CAD Import Module or one of the LiveLink products for AutoCAD Creo Parametric Inventor Pro ENGINEER SolidWorks or SpaceClaim and the File Import for CATIA V5 From To file via linked CAD package 88 Supported External File Formats ECAD FILE FORMAT READ WRITE NETEX G asc Yes No ODB X xml Yes No GDS gdx Yes No SPICE cir Yes No Requires one of AC DC Module RF Module or MEMS Module
74. s the settings for heat conduction and current conduction The contribution of the Joule Heating Model I node to the entire equation system is underlined in the Equation section The heating effect for Joule heating is set in the Electromagnetic Heat Source I node he Thermal Insulation node contains the default boundary condition for the heat transfer problem and Electric Insulation corresponds to the conservation of electric current The Initial Values node contains initial guesses for the nonlinear solver for stationary problems and initial conditions for time dependent problems 4 gt Joule Heating jh i Joule Heating Model 1 3 Electromagnetic Heat Source 1 a Boundary Electromagnetic Heat Source 1 Electric Insulation 1 A Thermal Insulation 1 3 Initial Values 1 eo o eb re Equation Equation form Study controlled Show equation assuming Study 1 Stationary pC pUtrans WT V kVT I 0 V J 0 J cE E VV 4 Joule Heating jh ES Joule Heating Model 1 Electromagnetic Heat Source 1 a Boundary Electromagnetic Heat Source 1 Te Electric Insulation 1 TE Thermal Insulation 1 tJ Initial Values 1 v Equation Show equation assuming Study 1 Stationary v 0 J ocE VV Thorough Example The Busbar 7 2 Right click the Joule Heating node In the second section of the context menu the boundary section select Heat Transfer in Solids gt Heat Flux
75. stprocessing menu Coerce to Subdomain Ideal constraint Non ideal constraint 94 New Terminology in Version 4 COMMENTS Parameters in 4 have a broader scope including the geometry Also predefined physical constants are new in version 4 Variables appear in two locations depending on their scope under Global Definitions with a global scope or under Definitions in each model In the latter case scope can be set to the entire model or to selected domains boundaries edges or points You find the coupling operators under Model Couplings in the Definitions branches A coupling operator as opposed to a coupling variable can be reused with different arguments For example the same coupling operator can be used to integrate different quantities over a boundary For hiding part of the geometry in the Graphics window The study type sets up a study step which controls the generation of a solver sequence for performing a certain type of study The Results branch contains the data sets for evaluation and visualizations of results as well as derived values plot groups for various plots tables for numerical results model reports and export of animations data files and images For converting geometry objects from one type to another for example from a solid to a curve A solid geometry consists of one or several domains In 4 2a available as a weak constraint and as a strong pointwise constraint In 4 2a
76. the Graphies toolbar then click the z Save button and name the model busbar mph E Keep input objects Keep cross sectional faces The root node is the same name as your file 0288 be O a amp i Model Builder gt S s Et el TO 4 09 busbar mph root gt Global Definitions gt l Model 1 modi gt W study 1 gt Results Distances from Work Plane Distances rm wbb Next create the titanium bolts by extruding two circles drawn in two work planes 70 Geometry Sequences 9 In the Model Builder right click Geometry I and add a Work Plane A Work Plane 2 node Is added In the Settings window under Work Plane select Face parallel as the Plane type HT Model Builder a busbar mph root 4 Global Definitions Fi Parameters 4 Model 1 mod t Definitions a A Geometry 1 a js Work Plane 1 wp a A Geometry m Rectangle 1 rt E Rectangle 2 r2 oy Difference 1 dif1 g Fillet 1 fit Ei Fillet 2 fil2 gt by View 2 Extrude 1 ext1 a 2 Work Plane 2 wp2 b gt A Geometry a a 10 n the Graphics window click face 8 highlighted in the figure Once this surface is highlighted in red right click anywhere in the Graphics window to add it to the Planar face list in the Settings window Face number 8 is now highlighted in blue and the work plane is positioned on top of face number 8 Click the Show Work Plane button to draw the first cir
77. these nodes are being edited In the Settings window under Element Size click the Custom button a E Meshes E Mesh1 a E9 Mesh 23 Size Free Tetrahedral 1 Mesh Sequences 37 5 Under Element Size Parameters enter mh 2 in the Maximum element size field and mh 2 mh 6 in the Minimum element size field Enter 0 2 in the Resolution of curvature field Click the Build All button 6 In order to keep this model in a separate file for later use save the model with a new name busbar_I mph Compare Mesh and Mesh 2 by clicking the respective node The mesh is updated in the Graphics window An alternative for using many different meshes is to run a parametric Calibrate for Pete Custom Element Size Parameters Maximum element size mh 2 m Minimum element size m Maximum element growth rate 15 Resolution of curvature 02 Resolution of narrow regions 05 sweep of the parameter for the maximum mesh size mh that was defined in Global Definitions Mesh 38 Mesh Sequences Mesh 2 Adding Physics to a Model COMSOL s distinguishing characteristics of adaptability and compatibility are prominently displayed when you add physics to an existing model In this section you will understand the ease with which this seemingly difficult task is performed By following these directions you can add structural mechanics and fluid flow to the busbar model STRUCTURAL MECHANICS A
78. ting Interface Identifier Domain Selection Selection All domains Equation Physical Model E Surface to surface radiation E Radiation in participating media Ea Reports E Porous media and mixtures Port Sweep Settings El Activate port sweep Click any associated node to return to a specific Settings window There is no longer the need to open multiple windows resulting in a streamlined workspace As you create the model each step is recorded in the Model Builder If for example your model required a certain sequence of steps to get the right geometry these are all listed in the order you set See the Geometry section in the figure above Even better this series of steps can be edited and rerun without having to repeat the entire simulation Complicated solver sequences you may need for different studies also benefit greatly from this feature As you work with the COMSOL Desktop and the Model Builder you will grow to appreciate the organized and streamlined approach But any description of a user interface is inadequate until you try it for yourself So in the next few sections you are invited to work through some examples to familiarize yourself with the next generation of simulation software 6 Capture the Concept Thorough Example The Busbar Electrical Heating in a Busbar In order to get acquainted with COMSOL Multiphysics it is best to work through a basic example step by step These i
79. tion that goes smoothly from O to in 0 5 seconds to find out how functions can be defined and verified Parameters Functions Variables and Model Couplings 29 DEFINING FUNCTIONS l Right click the Global Definitions node and select Functions gt Step 7T IT Model Builder gt E s Et Bt WO 4 busbar mph root Global Definitions a i Model a Variables i Functions zt Analytic A Ge at lt Interpolation b Dynamic Help saa i Piecewise EJ Joule Heating Model 1 D j External t Electromagnetic Heat Source 1 Gaussian Pulse MATLAB a Boundary Electromagnetic Heat Source a Electric Insulation 1 tf A Thermal Insulation 1 Ramp Random P Initial Values 1 oe Heat Flux 1 Rectangle D Electric Potential 1 ng A Ground 1 J i Step G ES Mesh1 TA Triangle et ee E 2 In the Settings window enter 0 25 in the Location field to set the location of the middle of the step where it has the value of Settings 0 5 T Step 3 Click Smoothing and enter 0 5 in Size of the Function Name Transition zone to set the width of the Fiennes aie smoothing interval 4 Click the Plot button TERE F From 0 To T Smoothing Size of transition zone W 0 5 30 Parameters Functions Variables and Model Couplings If your plot matches the one below this confirms that have defined the function correctly step1 t
80. utton x Thorough Example The Busbar 2 MESH The simplest way to mesh is to create an unstructured tetrahedral mesh which is perfect for the busbar Alternatively you can create several mesh sequences as shown in Mesh Sequences on page 37 A physics controlled mesh is created by default In most cases It is possible to skip to the Study branch and Just solve the model For this exercise the settings are investigated in order to parameterize the mesh settings Inthe Model Builder click the Mesh I node amp it Settings gt u im In the Settings window select User controlled mesh from the Sequence type list e Mesh 2 Click the Size node 43 under Mesh I Be Sequence type Physics controlled mesh Mermal a E Mesh1 amp a Size l 2 Free Tetrahedral 1 3 In the Settings window click the Custom 524 Settings Tao button under Element Size The stars that aa Al Size display in the upperright corner of the icons indicate that these nodes are being Element Size edited Calibrate for Enter mh in the Maximum element size field General physics Enter mh mh 3 in the Minimum element size Predefined Normal field and enter 0 2 in the Resolution of J Custom curvature field Notice that mh is 6 mm the value entered earlier as a global ma Maximum element size parameter amp m By using the parameter mh the variations in Minimum element size mh mbh 3 mi
81. vuppored Externa PICTON WalSes ql dtd aati pases 89 Keyboard SNORCUIS aii matacv ieee Misa ee has JA New Terminology in Version 4 uaaa a a J3 Introduction Computer simulation has become an essential part of science and engineering Digital analysis of components in particular is important when developing new products or optimizing designs Today a broad spectrum of options for simulation is available researchers use everything from basic programming languages to various high level packages Implementing advanced methods Though each of these techniques has its own unique attributes they all share a common concern Can you rely on the results When considering what makes software reliable it s helpful to remember the goal you want a model that accurately depicts what happens in the real world A computer simulation environment is simply a translation of real world physical laws into their virtual form How much simplification takes place in the translation process helps to determine the accuracy of the resulting model It would be ideal then to have a simulation environment that included the possibility to add any physical effect to your model That is what COMSOL is all about It s a flexible platform that allows even novice users to model all relevant physical aspects of their designs Advanced users can go deeper and use their knowledge to develop customized solutions applicable to their unique circumstances With this kind of all
82. w name Fluid Flow Single Phase Flow Laminar Flow spf 2 Turbulent Flow Creeping Flow spf Rotating Machinery Fluid Flow Ss Pipe Flow pfl E Thin Film Flow Multiphase Flow F Porous Media and Subsurface Flow Non Isothermal Flow E gt High Mach Number Flow AS Barefierd Flans busbar_box_I mph 3 On the Graphics toolbar click the Wireframe rendering button to look inside the box X SeGS QQReEA L bk ek eoo ea Culm a 48 Adding Physics to a Model Now that you have added fluid flow to the model you need to couple the heat transfer part of the Joule Heating physics interface to the fluid flow 4 n the Model Builder right click Joule Heating In the first section of the context menu at the domain level select Heat Transfer in Solids gt Heat Transfer in Fluids a Joule Heating jh ES Joul Joule Heating Model De Heop Electromagnetic Heat Source im Bo ae D Elec Infinite Elernents t The Initial Values ta Initi Heat Transfer in Solids Heat Transfer in Solids op Hea Electric Currents Heat Transfer in Fluids a0 Elec a Gro Boundary Electromagnetic Heat Source E SOE 3 Mlechd peece nag a ree 5 The Settings window for Heat Transfer in Fluids displays S Heat Transfer in Fluids Domain Selection t Override and Contribution t Equation 6 In the Graphics window select the air domain to highlight it in
83. window under Expression click the Replace Expression button amp Select Joule Heating Electric Currents gt Currents and charge gt Current density norm jh norm This is the variable for the magnitude or absolute value of the current density vector 8 Click the Plot button 4 The resulting plot is almost uniform due to the high current density at the contact edges with the bolts Left click and drag the busbar in the Graphics window to view the back of the busbar On the Graphics toolbar click the Go to Default 3D View button she Manually change the color table range to visualize the current P density distribution Vv 8 7983 Thorough Example The Busbar 2 9 Click Range and select the Manual color range Range check box Enter 1e6 in the Maximum field Manual color range Minimum 0 Maximum eb Click the Plot button and save the model as busbar mph I Li I l 1 I I 1 1 J I I I 1 1 1 1 I 1 I l The resulting plot shows how the current takes the shortest path in the 90 degree bend in the busbar Notice that the edges of the busbar outside of the bolts are hardly utilized for current conduction 8 7983 l0 Rotate the image to view the back of the busbar where you can see the high current density around the contact surfaces of the bolts Continue the exercise by adding your own plots to investigate ways to generate cross section plots and cross section line plots Now you
84. ywhere in the Graphics window to remove this boundary from the Selection list Repeat this for the other two bolts Cross check Boundaries 8 15 and 43 are removed from the Selection list To display the boundary labels click the View I node L under Definitions in the Model Builder and then select the Show geometry labels check box To view a list of all boundaries choose Selection List from the View menu 5 In the Settings window click the Inward heat Th i si Ux flux button Enter htc in the Heat transfer Bona coefficient field h Inward heat flx qoh Tar T Heat transfer coefficient h hte Wiim K External temperature Text 293 15 K K Continue by setting the boundary conditions for the electric current Thorough Example The Busbar 9 6 n the Model Builder right click the Joule Heating node In the second section of the context menu the boundary section select Electric Currents gt Electric Potential T Model Builder 4 busbar mph root b Global Definitions 4 Modell modi gt Definitions gt YA Geometry 1 b Materials Joule Heating Model Electromagnetic Heat Source J Infinite Elements J Initial Values gt gt In Heat Transfer in Solids Gm H Electric Currents b amp B Mesh gt Study 1 c Boundary Electromagnetic Heat Source gt Results p Periodic Condition Heat Transfer in

Introduction to COMSOL Multiphysics®

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Introduction to COMSOL Multiphysics®