ESTEL-3D v5p6 User Manual
Contents
1. 1 L PO e VX Darcian Velocity Vx L T PO This document is a draft 3 PDF file created on 4 12 2006 ESTEL 3D v5p6 User Manual e VV Darcian Velocity Vy L T PO e VZ Darcian Velocity Vz L T PO e ZG Elevation L P1 e HH Hydraulic Head L P1 e IMAT Soil Type PO See section 10 1 for more information about the discretisation types Note that the soil type IMAT variable as well as the coordinate X Y and Z are always output in the 3D results file Also note that although this keyword lists the variables to output it is not a keyword list the syntax is that of single character string where variables are separated by commas rather than a list of character strings FILE FORMAT FOR THE 3D OUTPUT FILES 2 int 1 This keyword spec ifies whether the 3D results file and the mesh results file will be written in ASCII or binary mode The choices are e 1 TECPLOT ASCII e 2 TECPLOT BINARY In the official commercial version of ESTEL 3D the default value is ASCII output value 1 This is due to concerns with the redistribution of the Tecplot library It is very likely that this default value has been changed to binary on your platform Check with your distributor Note that binary output files take a lot less file soace than ASCII files However they can only be read with the Tecplot software version 10 and above An ASCII output file can be read with any fi2. These boundary conditions need to be specified for each boundary point Again because unstructured 3D data is complex to manipulate it is advan tageaous to use the data contained in the ICEM file as much as possible A number is given to each boundary face and in a similar way to what can be done for the soil types in section 6 these face numbers can be used in the user subroutines 7 2 Defining priorities for the boundary surfaces This section is an optional step when parameterising boundary conditions but it is advantageous to define priorities for the boundary faces so that a lot of the work can be done during the mesh generation stage A number is given to each boundary face in the universal file created with ICEM see section 4 However ESTEL 3D requires boundary information by point and boundary points can be located on more than one boundary face 16 ESTEL 3D v5p6 User Manual Therefore a priority list is used to decide which face to use This list is kept in the Fortran array FACE PR which contains NB_FACES elements NB_FACES is the number of external faces given in the steering file see section 2 4 The subroutine H3d_FACES from the file h3d_faces f is used to define the priority list for instance INTEGER INTENT IN NB_FACES INTEGER INTENT INOUT FACE_PR NB_FACES FACE_PR 7 12 2 3 4 5 8 9 10 11 1 6 It means that if a point is located both on faces 7 and 12 for instance the face number 7 will be used f
3. a standalone file or whitin the steering file itself at the user s convenience Below is an extract the file containg the soil database from the tracv3d test case SPACE AND TIME UNITS m s NUMBER OF SOILS 2 Soil 1 Soil 2 dummy Tracy VG SOIL MOISTURE MODEL 12 3 SATURATED MOISTURE CONTENT 0 45 0 75 RESIDUAL MOISTURE CONTENT 0 15 0 22 SATURATED CONDUCTIVITY KS111 10 1 e 12 SATURATED CONDUCTIVITV KS222 10 1 e 6 SATURATED CONDUCTIVITY KS333 10 1 e 09 SOIL MODEL PARAMETER SP1 10 10 SOIL MODEL PARAMETER SP2 0 1 e 8 SOIL MODEL PARAMETER SP3 0 ae SOIL MODEL PARAMETER SP4 0 100 SOIL MODEL PARAMETER SP5 0 100000 The SPACE AND TIME UNITS contains Note that if all these keywords are put directly in the steering file there is no need to repeat this keyword twice ESTEL 3D v5p6 User Manual The NUMBER OF SOILS is then required It will be used to dimension all other keywords which expect lists of values according to the following pattern NUMBER OF SOILS N Soil 1 Soil 2 Soil 3 Soil N PROPERTY Valuel Value2 Value3 ValueN e the saturated moisture content 0 e the residual moisture content 6 e the saturated conductivity along the x axis Krzr e the saturated conductivity along the x axis Ksyyy e the saturated conductivity along the x axis K The saturated conductivity tensor used by ESTEL 3D allows for anisotropy but has to be diag
4. for more detail Note that to facilitate the interpretation of the results it is important that the PRINTOUT PERIOD be a multiple of the time step and that INITIAL PRINTOUT TIME is of the form INITIAL TIME N TIME STEP where N is any integer 2 4 Domain geometry NUMBER OF EXTERNAL FACES N int none This keyword defines the number of external faces which constitute the boundary of the computa tional domain For instance for a cube N would be equal to six This num ber is required to fully parameterise an ESTEL 3D simulation so when using a complex geometry it is useful to write down the number of exter nal faces created by ANSYS ICEM PRIORITY FOR EXTERNAL FACES 5 6 2 3 4 1 list int none When a node belongs to two or more external faces it needs to be assigned a specific face number that will be re used when setting up the boundary This document is a draft 5 PDF file created on 4 12 2006 ESTEL 3D v5p6 User Manual conditions see chapter 7 The approach used in ESTEL 3D consists of defining a priority list for the external faces and use this list to determine which face number should be used For instance if a node belongs to faces 1 and 3 the example priority list above will assign the face number 3 to that node Note that the mesh results file can help you finding how the external face numbers are distributed on the mesh This is described in section 10 2 This section describes keywords which describes the physics o
5. of the file which contains the soil data base file which is described in more details in section 6 Note that the soil database can be included in the sterring file 2 2 Output files and variables This set of keywords is used to tell ESTEL 3D which variables to save in the results files and which file names to use 3D RESULTS FILE file dat char none This keyword is used to give the name of the results file The 3D results file is written in either binary usual extension plt or ASCII usual extension dat Tecplot datafile format See THE FILE FORMAT FOR THE 3D OUTPUT FILES keyword below for a description of the keyword to switch between binary and ASCII output Section 10 1 contains a more in depth description of the 3D results file VARIABLES FOR 3D GRAPHICAL PRINTOUTS H VX VY VZ char H THETA IMAT This keyword is used to list the variables to output in the 3D results file The character string contains a list of variables separated by commas The key is e Example NAME Full Name Of Variable Unit Discretisation e H Pressure Head L T P1 e THETA Volumetric Moisture Content L3 L3 PO e KXX Hydraulic Conductivity Kxx L T PO e KYY Hydraulic Conductivity Kyy L T PO e KZZ Hydraulic Conductivity Kzz L T PO e KUNSAT Relative Unsaturated Hydraulic Conductivity PO e SAT Effective Saturation PO e CAP Hydraulic Capacity
6. phase Therefore the user needs to have a good idea of the soil distribution and the boundarv conditions when building the mesh with the software ANSVS ICEM CFD so that he can define a specific colour to the soil tvpes and boundarv conditions ESTEL 3D requires two files from ANSVS ICEM CFD the universal file which contains the mesh definition and the log file which contains a summary of the information contained in the universal file such as number of points number of elements etc The mesh created with ANSYS ICEM CFD can be slightly modified at the beginning of an ESTEL 3D simulation This can be used to convert the length unit or perform simple manipulations such as moving the origin of the coordi nate system These modifications can be done in the subroutine user_correct_xyz The user can modify the arrays x x and x for each of the npoin points in the mesh integer intent in npoin Number of points double precision intent inout x npoin l X coordinates double precision intent inout y npoin l V coordinates double precision intent inout z npoin l Z coordinates For instance to scale the mesh and change the origin of the coordinate svstem translation one could use integer ipoin do ipoin 1 npoin I Scale the mesh from m to km for instance 10 ESTEL 3D v5p6 User Manual x ipoin x ipoin 1000 y ipoin v ipoin 1000 z ipoin z ipoin 1000 Move the origin 50 m up 50 m
7. the iterative process after a N iteration even if the accuracy has not been reached N 200 is usually a good guess This document is a draft 7 PDF file created on 4 12 2006 Chapter 3 The Fortran file 3 1 Background All numerical models in the TELEMAC system have the option of having part of the program recompiled at the beginning of a simulation This is a verv powerful feature as it means that the user is not limited to the situation thought of bv the developer and can use its own code The subroutines that can be recompiled at runtime are called the user subroutines In ESTEL 3D these subroutines are all put inside one single module called MEESTEL3D_USERPROCS This chapter lists all available subroutines and each subroutine is described in de tail in the following chapters To make use of the user subroutines the file M ESTEL3D USERPROCS f90 needs to be copied to the simulation folder It is then usually renamed some thing like fortran f90 And the new name given to the FORTRAN FILE keyword in the steering file Now the whole module will be recompiled at the beginning of a simulation Each subroutine inside this module is blank and the sections that can be edited are marked as follows 3 2 List of user subroutines user_correct_xyz is used to modify the mesh This can be useful to manip ulate the coordinates created by the mesh generator for instance to change scale by converting metres to kilometres etc This subroutine i
8. 0 05 km z ipoin z ipoin 0 05 enddo Note that user_correct_xyz cannot be used to modify the mesh connectiv ity table i e the nodes can be moved around the but the segments still link the same nodes Obviously if the user code entered in user_correct_xyz creates intersections between segment or faces the simulation will stop as the mesh is not valid anymore This document is a draft 11 PDF file created on 4 12 2006 Chapter 5 Distribution of the soil tvpes on the mesh The distribution of the soil tvpes on the grid is done via the user subroutine user correct soils The soil tvpe for each element of the mesh is contained in the Fortran arrav imat integer intent in nelem Number of mesh elements Final mesh distribution integer intent inout imat nelem The user has to give an integer value to each element of the mesh This integer value corresponds to a soil type of the soil database see chapter 6 To achieve this the user should capitalize as much as possible on the work done during the mesh generation and use the element colours defined in AN SYS ICEM CFD These colours are automatically read by ESTEL 3D and are made accessible to the user via the Fortran array imat Element colours in the UNV file integer intent in nsol nelem Then imat can be from nsol using simple Fortran statement for instance integer ielem do ielem 1 nelem imat ielem nsol ielem enddo Obviously the ICEM
9. EL 3D buses an iterative scheme to solve it This section describes the keywords related to the iterative scheme SCHEME FOR SOLVING THE RICHARDS EQUATION 1 int 2 Two schemes are available the classic Picard scheme and the modified Picard scheme The modified scheme is meant to be more performant more stable and requires less iterations but users have had problems with it hence the classic Picard scheme is still the default scheme e 1 MODIFIED PICARD SCHEME This document is a draft 6 PDF file created on 4 12 2006 ESTEL 3D v5p6 User Manual e 2 CLASSIC PICARD SCHEME CONVERGENCE CRITERION OF THE ITERATIVE SCHEME 2 int 2 Different types of convergence criteria can be used to stop the scheme iterating The dictionnary cites three choices e 0 ALWAYS CONVERGENCE e 1 RELATIVE CONVERGENCE CRITERION e 2 ABSOLUTE CONVERGENCE CRITERION However in ESTEL 3D v5p6 only the absolute convergence criterion is available Do NOT use option 0 or 1 they are only provided for de bugging purposes at this stage ACCURACY OF THE ITERATIVE SCHEME FOR THE RICHARDS EQUATION 1 E 4 real 1 E 4 This keyword sets a value for the convergence cri terion defined above Assuming you are using the absolute convergence criterion and you should the accuracy is expressed in the length unit i e m by default When the offset between two successive iterations of the iterative scheme is less than the required accurac
10. ESTEL 3D version 5 6 User Manual JP Renaud Universitv of Bristol December 4 2006 Chapter 1 Introduction ESTEL 3D is a numerical model for flow and contaminant transport in porous media ESTEL 3D is developed bv EDF where it is used to look at the viabilitv of a deep nuclear waste repositorv in collaboration with the Universitv of Bris tol where ESTEL 3D is used for subsurface hvdrologv research ESTEL 3D is part of the TELEMAC system TELEMAC is a state of the art hvdroinformatics svstem comprising several modules for water flow sediment transport water qualitv and waves In particular the TELEMAC svstem con tains the Blblioth que l ments Finis BIEF a powerful finite element library shared by all modules The BIEF library handles numerical operations Like all other modules in the TELEMAC system ESTEL 3D is written in FORTRAN 90 In version v5p6 ESTEL 3D contains a prototype module solving the advec tion dispersion equation for solute transport using the random walk method This module is not feature conmplete and will not be described in this user manual Please read chapter 12 if you wish to use this experimental feature ESTEL 3D solves the partially saturated Richards equation in its mixed form 90 a L EN h z 9 is the moisture content K the conductivitv tensor h the pressure head z the elevation and t the time Richards equation is usually written with an additional source sink S term but this ter
11. ad on two faces This document is a draft 17 PDF file created on 4 12 2006 ESTEL 3D v5p6 User Manual Variable for the loops INTEGER IPTFR Put the whole boundary to no flux LIHBOR Neumann and QBOR O DO IPTFR 1 NPTFR LIHBOR IPTFR KNEU QBOR IPTFR 0 DO ENDDO Set faces 5 and 6 to imposed head LIHBOR Dirichlet and HBOR imposed values DO IPTFR 1 NPTFR IF FACE FOR BNODE IPTFR EQ 5 THEN LIHBOR IPTFR KDIR HBOR IPTFR imposed head face 5 ELSE IF FACE FOR BNODE IPTFR EQ 6 THEN LIHBOR IPTFR KDIR HBOR IPTFR imposed head face 6 ENDIF ENDDO This example shows that if particular care is given to the boundarv faces numbering during the mesh generation the information can be used verv easilv when parameterising ESTEL 3D This document is a draft 18 PDF file created on 4 12 2006 Chapter 8 Initial conditions Chapter 9 Running ESTEL 3D Running ESTEL 3D is done at the command line in a similar way to all other modules of the TELEMAC system Just call estel3d with the name of the steering file Note that if no steering file name is given ESTEL 3D uses by default a steering file called cas estel3d name of steering file ESTEL 3D will then run in the shell window where it has been started and print running messages to the screen 20 Chapter 10 Output files in depth 10 1 ESTEL 3D results file ESTEL 3D writes its results in a binary file called res tecbin p
12. colours can be overidden if necessessary for instance to use soil number 1 for the colours 1 and 2 and soil number 2 for the colour 3 one could use integer ielem do ielem 1 nelem if nsol ielem eq 1 imat ielem 1 12 ESTEL 3D v5p6 User Manual if nsol ielem eq 2 imat ielem 1 if nsol ielem eq 3 imat ielem 2 enddo More complex operations can be done on the array imat using the mesh coordinate for example but as manipulating unstructured 3D data is complex we recommend using the ANSYS ICEM CFD colours as much as possible Note that if one soil type only is required in the simulation ESTEL 3D will use the soil number 1 from the soil database by default The index of the de fault soil can be changed with the keyword INDEX OF THE UNIFORM SOIL In any case the index of the unifor soil is given to all elements before call ing user correct soils Therefore the keyword can be used to give a default value to all elements and only those who require modification are modified in user_correct_soils This document is a draft 13 PDF file created on 4 12 2006 Chapter 6 Definition of soil properties 6 1 Syntax The soil properties are kept in the soil database file which is a text file whose name is specified in the steering file via the kevword FILE CONTAINING THE SOIL DATABASE The svntax of the file is similar to that of the steering file i e it consists of a list of keywords The soil database can be in
13. eywords used in a typical simulation The keywords have been grouped by function input files output files numeri cal parameters physical parameters etc 2 1 Input files This first set of keywords tells ESTEL 3D where to find information such as the geometry of the domain for example FORTRAN FILE file f90 char none This keyword is used to give the name of the Fortran file extension 190 The Fortran file is compiled when the ESTEL 3D v5p6 User Manual simulation starts and contains a Fortran module This module contains all subroutines that the user can modify for his simulation An in depth description of the Fortran file is given in chapter 3 ICEM LOG FILE file log char none This keyword is used to give the name of the log file usual extension log for the mesh in UNiVersal format see below This file is created automatically by the ANSYS ICEM CFD soft ware when generating a mesh The log file contains summary information about the mesh such as number of nodes elements etc Although it is a text file this file should NOT be edited manually UNIVERSAL FILE file unv char none This keyword is used to give the name of the mesh in UNiVersal format usual extension unv This file is usually created using the ANSYS ICEM CFD software Although it is a text file it should NOT be edited manually FILE CONTAINING THE SOIL DATABASE sdb char none This keyword is used to give the name
14. f the flow to be modelled 2 5 Extra physical parameters INDEX OF THE UNIFORM SOIL N int 1 This keyword defines which soil of the soil data base by default soil 1 is to be used by default for all elements of the mesh More information about soils is given in chapter 6 for the soil database and chapter 5 for the soil distribution 3D DIRECTION OF GRAVITY 0 0 1 list real 0 0 1 This keywords expects a list of three reals which define the components of a vector grav ity g on the axis x y and z The modulus of the vector does not matter and only its direction is used i e 0 0 1 and 0 0 45 produce the same result However using 0 0 12 would define an upward gravity vector INFLUENCE OF GRAVITY yes bool yes The influence of gravity can be switched on or off using this keyword Note that switching the gravity off has no physical meaning in a 3D code and this option is usually used only to compare the results with the analoguous heat transfer equation for which many analytical solutions exist 2 6 Numerical parameters This final set of keywords is used to control how the equation is actually solved The values of these keywords can be modified to match particular require ments However the values used in this document usually the default values are a good starting point for any simulation 2 6 1 Iterative scheme As Richards equation is highly non linear in unsaturated conditions EST
15. le editor TITLE Title of the simulation char No title in the steering file The title is a simple character string which will be written on the screen when ESTEL 3D runs and will be written in the results file STOP AFTER CREATING THE MESH RESULTS FILE yes bool no Sometimes it is difficult to parameteris an ESTEL 3D simulation as the geometry is so complex that the external faces are difficult to visualize It is now possible to ask ESTEL 3D to interpret the mesh save the results in the mesh results file see below and then stop the simulation This allow a direct visualisation of complex meshes as interpreted by ESTEL 3D 3D MESH RESULTS FILE file dat char none This keyword is used to give the name of a file which will contain a version of the mesh after it has been interpreted by ESTEL 3D see above A more detailed description of this file is given in section 10 2 2 3 Simulation duration and time control This section lists the time related keywords for a ESTEL 3D simulation This document is a draft 4 PDF file created on 4 12 2006 ESTEL 3D v5p6 User Manual SPACE AND TIME UNITS m s char m s This keyword is used to define respectively the length and time units Each unit is a character string of four characters at most Note that the units defined in the steer ing file have to match the units defined in the soil database file see sec tion 6 so that the conductivit
16. lt It is written in Tecplot 10 format It contains one zone with the following variables X Y Z Spatial coordinates L H Pressure head ZL VX VY VZ Components of the Darcian velocity L T 1 KSXX KSYY KSZZ Diagonal component of the saturated conductivity tensor IL T 1 KUNSAT Relative conductivity When the keyword ASCII TECPLOT OUTPUT is set to yes another re sults file named result_tec dat is also created It is an ASCII version of tec resbin plt and could be used for a conversion to any other format Refer to the Tecplot documentation for information on how to use Tecplot to explore the ESTEL 3D results and a description of the file format 10 2 Mesh results file 21 Chapter 11 ESTEL 3D infrastructure 22 Chapter 12 More information and Feedback 12 1 This document The latest version of this document is available in PDF format at the URI titi A working copy in ATEX format is available from the Subversion repository at Bristol University at the URI http source ggy bris ac uk subversion estel doc branches REL v5p6 estel3d um tex Note that vou will need a username and password to download this document 12 2 The particle tracking module A prototvpe of the particle tracking module is present in ESTEL 3D v5p6 How ever it is still eveolving a lot and we do not recommend using it vet If vou reallv want to use it look at the text case cube partjin the test gb directory You sho
17. m is not activated in version v5p6 ESTEL 3D solves equation by the finite element method on an unstructured mesh of tetrahedra It is a partial differential equation and requires both initial and boundary conditions Chapter 2 The steering file An ESTEL 3D simulation is controlled via a steering file The steering file is a text file which contains a list of keywords All keywords available in ESTEL 3D are described in this chapter The keywords have been grouped by function input files output files numerical parameters physical parameters etc For each keyword the syntax used in this manual is KEVWORD example type default value Description of the keyword The keywords can be of type integer int real real boolean bool or character string char written inside quotes char The default value is the value which will be used by ESTEL 3D if the keyword is not found in the steering file When none is written as the default value it means that the key word has to be included in the steering file Note that in the steering file the equal signs could be subsitituted with colons Therefore you might find that some people use the syntax KEYWORD value Note that some keywords e g see SPACE AND TIME UNITS expect more than one value In that case the values should given separated by a semi colon y and the type in the the description will contain the term list The following section describe the k
18. onal The general form of the saturated conductivity tensor should be Kei 0 0 K 0 K 5222 0 0 0 K 5333 Therefore the main axis of anisotropy have to be parallel to the coordinate axis This is a limitation when using ESTEL 3D in stratified media where the stratification is diagonal The third line in the SOIL block contains five parameters which define the soil moisture curve In our case the storage coefficient is the first parameter In steady state mode it will have no effect on the flow The other four parameters can have any value they will not be used by ESTEL 3D 6 2 Soil models 6 2 1 Constant storage 00 Oh 6 2 2 Van Genuchten 6 3 Tracy model DO NOT USE This document is a draft 15 PDF file created on 4 12 2006 Chapter 7 Boundarv conditions The boundarv conditions are defined with the user subroutines H3D BORD and H3D FACES contained in h3d_bord f and h3d faces f 7 1 Background Three tvpes of boundarv conditions are available in ESTEL 3D version 5 5 Dirichlet The Dirichlet boundarv condition represents an imposed head i e the value of the pressure head is know at the boundarv Neumann The Neumann boundary condition is an imposed flux It is used to specify how much water enters the domain though a section of the boundary Cauchy The Cauchy condition is an imposed flux that depends on the value of the pressure head inside the domain It is very rare and will not be described in this document
19. or this point 7 3 Defining the boundary conditions The boundary conditions are defined in the subroutine H3D_FACES from the file h3d_faces f Three Fortran arrays are used to hold the boundary conditions in ESTEL 3D INTEGER INTENT INOUT LIHBOR NPTFR DOUBLE PRECISION INTENT INOUT HBOR NPTFR DOUBLE PRECISION INTENT INOUT QBOR NPTFR NPTFR is the number of boundary points and LIHBOR is used for the type of boundary condition To select a Neumann boundary condition for the boundary point IPTFR just use LIHBOR IPTFR KNEU where KNEU stands for Neumann Similarly KDIR is used for Dirichlet points Dirichlet points require an imposed pressure head this is done with the array HBOR Neumann points require an imposed flux this is done with the array QBOR So to define an imposed flux on 1 e 6 at the boundary point IPTFR one could use LIHBOR IPTFR KNEU QBOR IPTFR 1 e 6 Because locating boundarv points on the 3D mesh is complicated it is ad vantageous to use the faces defined during the mesh generation as much as possible This can be done by using the array FACE FOR BNODE which contains a face number for each boundarv node When a boundarv node belongs to several faces the face with the highest prioritv is used This allows the user to impose face wise boundary conditions very quickly For instance for a cube one could use the following code to impose a impermeable boundary on 4 faces and an imposed he
20. s described in more details in section 4 ESTEL 3D v5p6 User Manual user_correct_soils is used to distribute the soil types on the mesh This sub routine is described in more details in section 5 The soil types them selves are described in chapter 6 user boundary conditions is used to define the boundary conditions This subroutine is described in more details in chapter 7 user initial conditions is used to define the initial conditions This subroutine is described in more details in chapter 8 3 3 Particle tracking subroutines Note that in the module M ESTEL3D USERPROCS two extra subroutines are listed user new particles and user dispersion These subroutines are used by the particle tracking module and not described in this manual If you want to use them please refer to section 12 2 3 4 Required Fortran knowledge Basic knowledge of the Fortran language is required to use ESTEL 3D You should be comfortable with if statements and array structures Extra knowl edge of Fortran would help you setting up more complex cases This document is a draft 9 PDF file created on 4 12 2006 Chapter 4 Definition of the mesh Generating the mesh is probablv the most complicated step of setting up an ESTEL 3D simulation Because unstructured meshes of tetrahedra are verv complex it is often not convenient to use Fortran subroutines to modifv spa tiallv distributed input and these operations have to be done during the mesh generation
21. uld really be using v5p7 or later though 12 3 Bugs By the time you read this user manual ESTEL 3D v5p7 or later will be in heavy development If you encounter a bug or think a feature does not work as adver tised it is likely that this has been addressed in the next version of ESTEL 3D However you are highly encouraged to get in touch with the developers so that your feedback helps them make ESTEL 3D even better for the next release 12 4 Contacting people If you need to report a bug have a question about some particular feature please use the following contacts 23 ESTEL 3D v5p6 User Manual JP Renaud University of Bristol j p renaud bristol ac uk Main developer at the University of Bristol Contact Jean Philippe with any general question about ESTEL 3D any bug report or feature request Regina Nebauer EDF regina nebauer edf fr Main developer and in charge of ESTEL 3D at EDF Contact Regina for any general question any bug report or feature request and also pur chasing licensing information This document is a draft 24 PDF file created on 4 12 2006
22. y the scheme stops MAXIMUM NUMBER OF ITERATIONS FOR THE ITERATIVE SCHEME 30 int 40 This keywords sets an upper limit to the number of iterations al lowed before convergence of the iterative scheme Note that if this maxi mum number of iterations is reached the simulation stops IMPLICITATION FOR THE PRESSURE HEAD 0 85 real 0 55 A semi implicit time formulation is used throughout ESTEL 3D This keyword is used to set the level of implicitation With a value of 1 the scheme is fully im plicit With a value of O it is fully fully explicit A value slightly higher than 0 5 is usually best Note that if you experience problems you can safely increase its value to get closer to 1 It usually helps 2 6 2 Numerical solver ESTEL 3D uses solvers from the BIEF library to handle the numerics All meth ods offered by BIEF are offered in ESTEL 3D Read the BIEF documentation for a detailed description of the relevant options This section merely lists the relevant keywords SOLVER FOR THE RICHARDS EQUATION 1 This keyword is used to choose which solver is used to solve Richards equation The list of available solvers is available from the BIEF documentation ACCURACY OF THE SOLVER FOR THE RICHARDS EQUATION 1 E 12 This keyword is used to fix the accuracy of the solver for Richards equation MAXIMUM NUMBER OF ITERATIONS FOR THE SOLVER FOR THE RICHARDS EQUATION N The solvers are iterative and this keyword can be used to stop
23. y value is matched to the mesh dimensions If they do not match the simulation will stop INITIAL TIME 0 real 0 Initial time for the simulation the initial conditions will be for the time specified with this keyword FINAL TIME 5 real 1 Final simulation time The simulation will stop when this time is reached TIME STEP 1 real 1 The time step is time increment used by ESTEL 3D to move forward in time For instance if the time usint is the second initial time is Os the final time 5s and the time step 1s then ESTEL 3D will use initial conditions at time Os and compute a solution of Richards equation for the timess 1s 2s 3s 4s and 5s PRINTOUT PERIOD 2 real 1 Simulation time period between output in the 3D results file INITIAL PRINTOUT TIME 0 real 0 Simulation time of the first printout STEADY STATE HYDROLOGY no bool no This keyword specifies whether ESTEL 3D is to be run in steady state or transient mode In steady state mode Richards equation simplifies a lot as the time derivative disap pears CONSTANT INITIAL CONDITIONS 1 real 0 When running in ESTEL 3D in transient mode Richards equation contains time derivatives Therefore it requires initial conditions This keyword can be used to impose a con stant value to all nodes in the mesh as initial conditions This is often not sufficient and more complex initial conditions can be programmed in the Fortran file See chapter 7
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