11. Using Convection Correlations
Contents
1. 9 Open a new window shell and in the directory which contains the database edit a file named template dat apnd creating the CONV definitions In unix create template dat Open a unix xterm window and change directories cd to the directory apnd file which contains your database If a template dat apnd already exists in this directory rename it to associate it with that previous analysis For instance in Exercise 10 you created a template dat apnd file Use the following unix command to move it to a new name associated with that analysis gt mv template dat apnd 10_template dat apnd Using the system editor create and edit the file template dat apnd in the directory which contains your database and where MSC PATRAN is running Following is a detailed description of what you will be entering into the file The actual entries are fairly brief and listed following the detailed description of the complete syntax Create two convection templates one for the forced_convection and the other for the natural_convection boundary condition The format for the CONV functions are as follows CONV TID config number_of_GP_values number_of_MPID_ values gp 2 gp 3 gp n mpid 1 mpid 2 mpid n Where TID The template ID number pointer you entered in the Load BCs form config Convection type configuration number Identifies the type of convection class e g 1 forced convection smooth Isothermal tubes 3 flat pl2. EE Exercise 11 Using Convection Correlations MSC PATRAN Version 7 5 22 Jan 98 14 42 37 33 Fringe TIME 0 0000000000D 00 SECONDS S S ITERATIONS 163 nrO nrf0l Temperature NON LAYERED default_Fringe Maz 339 6 Nd 1090 Min 326 4 Nd 121 Objective m Model an iron cube m Apply convective boundary conditions using correlations from the MSC THERMAL convection correlation library m Runa steady state analysis and display results PATRAN 312 Exercises Version 7 5 11 1 11 2 PATRAN 312 Exercises Version 7 5 Exercise 11 Using Convection Correlations Model Description In this exercise you will determine the steady state temperature distribution in an iron cube MID 18 The temperature distribution will be driven by a heat flux on one vertical face natural convection on another vertical face and forced convection on the top horizontal face CONV definitions link convection Template ID s TID s which are applied in the Loads BC s form to convection configurations and associated Material Property ID s MPID s CONV definitions are edited into a template dat apnd file which you create in the same directory as your database MPID s for air will be placed in a mat dat apnd which you also create MSC PATRAN contains an extensive library of convection coefficient configurations The configurations are described in Chapter 9 Volume 1 of the MSC THERMAL Application Module User Manual This volume can be
3. Prepare and submit the model for analysis RE Prepare and Select the Analysis Applications radio button to prepare the analysis Select run analysis the parameter forms reviewing and changing the settings as shown below The analysis is submitted by selecting Apply in the Analysis form Analysis Analyze Full Model Full Run Translation Parameters Solution Parameters Run Control Parameters Initial Temperature Scale Kelvin Initial Temperature 300 0 Output Requests Units Scale for Output Temperatures Kelvin Nodal Results File Format Select Thermal Entries to Output lt select all 8 items listed gt Convection Resistors Diagnostic Output PATRAN 312 Exercises Version 7 5 11 15 Read and plot results OK Apply l 12 Read and plot the results Read and plot results From within MCS PATRAN the only indication that the analysis has successfully finished is the existence of an nr0 nrf 01 results file in a subdirectory one level below your working directory P3 was initiated from a working directory which contained the exercise_11 db database Applying the analysis created a new subdirectory with the same name as the Job Name exercise_11 By using Read Result in the Analysis form and Select Results File you can filter down to the Job Name subdirectory and check for the existence of a results file Analysis Read Results Result Entities Select Resul
4. accessed through the on line Help Document Library Figure 1 Forced Convection T 300 K V 10 m s Heat flux 1000 W m2 Natural convection Iron Cube Tamb 00 MID 18 g 9 81 m s PATRAN 312 Exercises Version 7 5 11 3 Exercise Overview 11 4 Create a new database named exercise_11 db Set Tolerance to Default and the Analysis Code to MSC THERMAL Create a 1m x 1m x Im solid Mesh the solid with an IsoMesh of Hex8 elements Global Edge Length of 0 100 Use Finite Elements Create Node Edit to create a boundary node not associated with geometry Apply element properties to the Hex8 elements defining them as Thermal 3D Solid and having a Material Name MID of 18 Create a spatial field which will provide distance from the leading edge data to the convection coefficient calculation Define a fixed temperature and heat flux boundary condition in Loads BCs Define two convection boundary conditions assigning each a different Convection Template ID and supplying the distance from the leading edge in the Convection Coefficient data box Open a new window shell and in the directory which contains the database edit a file named template dat apnd creating the CONV definitions In your xterm window shell and in the directory which contains the database copy an existing file lt P3_HOME gt p3thermal_files examples qtran prob4 mat dat apnd containing air MPID data to your directory P
5. ate forced convection etc number_of_GP_values Number of general properties needed for a specific convection configuration Example For config 3 forced convection over a horizontal surface GP 1 element surface area automatically supplied by MSC PATRAN GP 2 shortest distance form plate s leading edge to element GP 3 longest distance from plate s leading edge to element GP 4 free stream velocity PATRAN 312 Exercises Version 7 5 11 13 In unix copy a mat dat apnd file number_of MPID_ values Number of Material Property ID numbers used to point to material properties Example For config 3 mpid s point to MPID 1 fluid density p MPID 2 fluid dynamic viscosity u MPID 3 fluid specific heat C MPID 4 fluid thermal conductivity K Note CONV is a keyword and must be typed in uppercase Use the following table to help you define the convection templates for the forced and natural convection boundary conditions You should also review the definition of the convection configuration 3 and 13 in the MSC THERMAL USERS MANUAL Volume 1 Chapter 9 Conv Type TID config GP MPID MPID s order is important Natural 913 550100 550101 550106 550103 550105 Shown below is the final form of the template dat apnd file created for this exercise Note that any comment lines must be started with an in column 1 and make sure that there are no blank lines especially a
6. ect the Properties Applications radio button Set the Action Dimension properties and Type to Create 3D Thermal 3D Solid Enter Property Set Name Prop1 Select the Input Properties box Click in the Material Name box and enter 18 Select OK to close the form Click in the Select Members box and select Solid 1 in the viewport Select Add then Apply in the Element Properties form to complete the element property definition Properties Property Set Name Prop sid Material Name wm Select Members lt select Solid 1 in the viewport gt Apply 6 Create a spatial field which will provide distance from the leading edge data to the convection coefficient calculation In the forced convection boundary conditions the heat transfer coefficient varies as the thermal boundary layer develops from a leading edge One input to the convective correlation is the distance from the leading edge of the surface MSC THERMAL provides for spatial fields to define the element distance from the leading edge You will create a spatially varying field that will define the required distance Click on the Fields toggle Set the Action Object and Method to Create Spatial PCL Function Enter X_dist in the Field Name box Next click in the Scalar Function text box and select X from Independent Variable list box Since the global coordinate system s origin is located at a lower left corner of the Solid the simple function f x x represents
7. ection Coefficient data box Convection Coefficient lt select X_dist from the Spatial Fields list box gt Convection Template ID 93 Fluid Node ID 9999 Select Application Region In the Select Applications Region form select the top face Y normal of Solid 1 Geometry Filter Geometry Select Surfaces or Edges lt select the top face Y normal of Solid 1 Solid 1 4 as shown in Figure 1 gt Apply Repeat these steps for a New Set Name natural_convection Click in the Convection Coefficient data box Leave the Convection Coefficient blank Use a Convection Template ID of 913 and a Fluid Node of 9999 In the Select Applications Region form select the right face X normal of Solid 1 Solid 1 2 PATRAN 312 Exercises Version 7 5 11 11 Create two convection Template ID s With boundary conditions applied the model should appear as shown below FE FE nn nn i ir y 2 5 Ia OR ene EL Pb oe ir par Li PE i a nn ni ln HS i F ua F o ki f af are Bair a Ris es es ad Sig Fi d Por ho z 1 4 ee ia E y 4 f You may also choose to review your loads and boundary conditions using Utilities Thermal Thermal BCs Display Use Clear and Close in the Thermal BC Display form to revert to normal display Clear Close 11 12 PATRAN 312 Exercises Version 7 5 Exercise 11 Using Convection Correlations
8. own menu 11 18 PATRAN 312 Exercises Version 7 5
9. repare and submit the model for analysis specifying that it is a steady state that all calculations and output should be K and that all eight columns of nodal results are included in the nodal results file Read and plot the results Quit MSC PATRAN PATRAN 312 Exercises Version 7 5 Exercise 11 Using Convection Correlations Exercise Procedure 1 Open a new database named exercise_11 db Open a new Within your window environment change directories to a convenient database working directory Run MSC PATRAN by typing p3 in your xterm window Next select File from the Menu Bar and select New from the drop down menu Assign the name exercise_11 db to the new database by clicking in the New Database Name box and entering exercise_11 Select OK to create the new database MSC PATRAN will open a Viewport and change various Main Form selections from a ghosted appearance to a bold format When the New Model Preferences form appears on your screen set the Tolerance to Default and the Analysis Code to MSC THERMAL Select OK to close the New Model Preferences form Tolerance Default Analysis Code MSC THERMAL Ee aa ee 2 Create a lm x Im x Im solid Create solid Select the Geometry Applications radio button Create a solid using the geometry following Action Object and Method Create Solid XYZ Vector Coordinate List lt 111 gt Apply PATRAN 312 Exercises Version 7 5 11 5 IsoMesh
10. s shown in Figurel Load BCs Create Heating Element Uniform Option Fluxes New Set Name Flux Target Element Type 3D Input Data Heat Flux 1000 When selecting a surface the surface chosen will be highlighted Hold down the lt Shift gt key and use the right mouse button to cycle through surfaces that may overlap or share an edge Select Application Region Select Solid Faces lt select X normal face of Solid 1 Solid 1 1 use shift right mouse button to cycle pick if necessary gt Apply 8 Define two convection boundary conditions assigning each a Create two different Template ID and supplying the distance from the i leading edge in the Convection Coefficient data box convection Template ID s Create the convection coefficient boundary conditions with the Use Correlations option New Set Name forced_convection with a fluid node 9999 and a Template ID of 93 Apply the boundary condition to the top face Y normal of Solid 1 as shown in Figurel 11 10 PATRAN 312 Exercises Version 7 5 Exercise 11 Using Convection Correlations Spatial field X_dist will be used in the Convection Coefficient data field to supply the leading edge distance to the correlation Load BCs Option Use Correlations New Set Name forced_convection Target Element Type 3D Input Data In the Input Data form provide the Convection Template ID fluid node and Geometric Properties 2 and 3 via the Conv
11. t the end of the file Start typing from the first column and do no enter any blank lines CONV 93 3 1 4 10 0 550100 550101 550103 550105 CONV 913 13 4 5 1 0 1 0 0 0 9 8 550100 550101 550106 550103 550105 K er 10 In your xterm window shell and in the directory which In unix copy a contains the database copy an existing file lt path gt mat dat apnd p3thermal_files examples qtran prob4 mat dat apnd fi dat ap containing air MPID data to your directory lie Copy a mat dat apnd file into the same directory in which you ve created the template dat apnd file The commands are as follows gt which p3 11 14 PATRAN 312 Exercises Version 7 5 Exercise 11 Using Convection Correlations response gt lt path gt bin p3 gt cp lt path gt p3thermal_files examples qtran prob4 mat dat apnd A mat dat apnd should now reside in your database subdirectory This file contains more material properties than required This will not adversely affect the analysis Feel free to review the format and syntax of the mat dat apnd file You can use this file as a boiler plate for creating your own material properties file data The template dat apnd and mat dat apnd files are the only two files that may need to be created outside of the MSC PATRAN in order to complete an analysis As MSC PATRAN evolves the creation of this files will be absorbed within the MSC PATRAN interface 11
12. the horizontal distance from the leading edge of the top surface where the forced convection heat transfer will occur Click on Apply to create the field The natural convection coefficient calculation uses the characteristic length L of the vertical side This will be input in the template dat apnd file GP list which will be described later in the exercise 11 8 PATRAN 312 Exercises Version 7 5 Exercise 11 Using Convection Correlations Fields Create Spatial PCL Function Field Name X_ dist Independent Variable x Apply The field name should appear in the Existing Fields list box 7 Create fixed temperature and heat flux boundary condition in Loads BC s Select the Load BCs Applications radio button Create a fixed 300 K nodal boundary temperature named Tamb In the Input Data form define the fixed temperature In the Select Application Region form pick Node 9999 Load BCs Create Temperature Nodal Option Fixed New Set Name Tamb Input Data Fixed Temperature 300 0 Select Application Region Geometry Filter FEM Select Nodes lt select Node 9999 gt K 1 DT lt PATRAN 312 Exercises Version 7 5 Apply temperature and flux boundary conditions 11 9 Create two convection Template ID s Create a set name Flux of 1000 W m Apply the boundary condition to the left facing X normal surface of the solid Solid 1 1 a
13. the solid Select Viewing from the Menu Bar or use the ToolBar Iso 1 View icon to change to an isometric_view Named View Options Close or Eso IsoMesh the 3 Mesh the solid with an IsoMesh of Hex8 elements Global solid Edge Length of 0 1 Select the Finite Elements Applications radio button Set the Action Object and Type to Create Mesh Solid For the solid list select Solid 1 Finite Elements Create Mesh Solid Solid List The resulting model is shown below lt click on Solid 1 in the viewport gt 11 6 PATRAN 312 Exercises Version 7 5 Exercise 11 Using Convection Correlations 4 Use Finite Elements Create Node Edit to create a boundary node 9999 not associated with geometry Create a boundary In the Finite Elements form create a boundary node which is not associated sink node with geometry The node is numbered 9999 Locate the node at 1 3 1 3 0 5 Finite Elements Create Node Edit Node ID List 9999 O Associate with Geometry Node Location List 1 3 1 3 0 5 Apply Increase the display size of nodes Use either Display Finite Element or the associated ToolBar icon to change the node size Display Finite Element Node Size 6 lt use slider bar gt PATRAN 312 Exercises Version 7 5 11 7 Apply element properties A 5 Apply element properties to the Hex8 s defining them as Apply Thermal 3D Solid and having a material name MID of 18 element Sel
14. ts File Directories lt path gt exercise_11 Available Files nr0 nrf 01 pthermal_nod_T res_tmpl There may be a warning message regarding Qmacro select OK Reduce the node size using Node Size icon a 2 11 16 PATRAN 312 Exercises Version 7 5 Exercise 11 Using Convection Correlations After results are read in plot the results To plot the results use the Results Application radio button Select you results file Create Quick Plot Select Result Cases TIME 0 0000000000D 00 S Select the Fringe Attributes icon Display Element Edges Label Format Fixed Significant figures 4 lt use slider bar gt Apply The model should now appear as shown on the front panel of this exercise Feel free to plot the value of the heat transfer coefficient and other quantities using Select Fringe Result To plot the heat transfer coefficient data Form Type Basic Select Result Case 2 1 Time 0 0000000000D Select Fringe Results 6 1 Average Convection Coefficient Apply The nodal averaged h s are displayed in the viewport To view detailed convection resistor data look in qout dat 01 file in the Job Name subdirectory Search for string CONVECTIVE RESISTOR DATA PATRAN 312 Exercises Version 7 5 11 17 Quit MSC Patran 13 Quit MSC PATRAN Ceres Quit MSC To stop MSC PATRAN select File on the Menu Bar and select Quit from Patran the drop d
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