File Specification¶
In general, this first section of the main input file is used to direct Goma I/O through a series of named external files that contain information about the finite element mesh, the initial guess of a solution vector, and output options for saving solutions for continuation, remesh, etc. The required and optional input records are as follows:
FEM File¶
FEM file = <file_name>
Description / Usage¶
This required card specifies the name of the EXODUS II finite element mesh file. Any EXODUS II file name is permissible, as specified below.
- <file_name>
A file name of the form prefix.exoII. The prefix portion is any user-specified alpha-numeric string, which can be used as a problem-type descriptor. Preprocessors and postprocessors (like AVS) might require the “.exoII” suffix so it is a required part of the file designation. The maximum length of the file name is 85 characters.
Technical Discussion¶
This file contains the finite element discretization of the problem domain. Finite element mesh files from other preprocessors may be used with Goma as long as a translator from the preprocessor’s output format to the EXODUS II format is available to the analyst.
References¶
The EXODUS II format is documented in:
EXODUS II: A Finite Element Data Model, Schoof, L. A. and V. R. Yarberry, SAND92-2137, Sandia National Laboratories, Albuquerque, NM.
Output EXODUS II File¶
Output EXODUS II file = <file_name>
Description / Usage¶
This required card specifies the name of the output EXODUS II file. Any EXODUS II file name is permissible, as specified below.
- <file_name>
A file name of the form
*prefix*.exoII. The prefix portion is any user-specified alpha-numeric string, which can be used as an output file descriptor.
This EXODUS II file contains a replica of the input mesh and boundary condition information exactly as it was provided in the FEM file, but has appended to it the solution field information appropriate to the problem type. If the name of this output EXODUS II file <file_name> is identical to the name of the input EXODUS II file (as specified in the FEM file card), then no replication of the input mesh data is performed and any results are simply appended to it.
Technical Discussion¶
Although allowed, it is not advisable to make this file name the same as the file name input on the FEM file card.
References¶
The EXODUS II format is documented in:
EXODUS II: A Finite Element Data Model, Schoof, L. A. and V. R. Yarberry, SAND92-2137, Sandia National Laboratories, Albuquerque, NM.
Guess File¶
GUESS file = <file_name>
Description / Usage¶
This required card identifies the input file that provides the initial guess for the solution vector for continuation or time integration, where
- <file_name>
Specifies the exact name of the file and can be any file name.
The file <file_name> is read by Goma only if the value of the Initial Guess (next section on General Specifications) card is set to read. The current format of this ASCII file is a list of unformatted floating point numbers (the solution variable followed by the residual value for that degree of freedom) in the order of the unknown map; this is the same format as the file described in the SOLN file card. A solution file from a previous simulation may be used.
Technical Discussion¶
This file is typically a copy of the SOLN file thus being an exact replica of it. It represents the only way to continue a previous solution from an ASCII file. Typically a continuation proceeds from a converged solution but the result from an intermediate solution could also be used; the user is cautioned about the potential difficulties of restarting from non-converged solution. (See Initial Guess card about (re-)starting from a binary file.)
SOLN File¶
SOLN file = <file_name>
Description / Usage¶
This required card identifies the ASCII output file that will provide the initial guess for continuation or time integration, where
- <file_name>
Specifies the name of the output file, or if no file is desired, a value of no or none should be entered.
The current format of this ASCII file is a list of unformatted floating point numbers that includes every degree of freedom in the problem in the order specified in the unknown map. Other information (residual for that degree of freedom) may appear beyond the first column of numbers in this file that is sometimes useful in determining the name and location of the corresponding degree-of-freedom. If no or none is used in place of the file name, no ASCII information is written.
Technical Discussion¶
This file represents the primary ASCII output of the Goma solution vector and the primary way to continue or restart a solution from an ASCII file. (See Write Intermediate Solutions for related information.) When a continuation run is performed, this file is copied into the file specified in the GUESS file input card.
Brk File¶
Brk file = <file_name>
Description / Usage¶
- <file_name>
A Brk file in the brk file syntax with specifications for material blocks
This optional card specifies the name of the Brk file for this problem, if one does not exist goma will attempt to create one. The Brk file is used by the brk utility to break the Exodus II files on parallel runs for each processor.
Warning
Brk files can only be created on single processor runs.
Write Intermediate Results¶
Write Intermediate Results = {yes | no}
Description / Usage¶
This optional card controls the output of intermediate results. The permissible values for this card are
- yes
The code will output the latest Newton iteration to a file named ‘tmp.i.d’, where i is the Newton iteration number. The format of tmp.i.d will be similar to the ASCII results data described for the GUESS file and SOLN file cards. Also, the output EXODUS II database (see the Output EXODUS II file card) will accumulate the intermediate iterations as time planes of the solution.
- no
No intermediate results are written; only the last Newton iteration is written to the file named in the SOLN file card, and only the final converged iteration is output to the EXODUS II file.
Technical Discussion¶
This file is useful to guard against machine crashes or accidental job kills, particularly for very large problems, as it can be used to restart a simulation (by using this file as the Guess file). The intermediate results in the output EXODUS II database can be a useful debugging tool, giving the analyst the ability to use highly relaxed Newton iterations to see how a free boundary problem diverges.
Write Initial Solution¶
Write initial solution = {yes | no}
Description / Usage¶
This optional card controls the output of an initial solution prior to the start of a time dependent simulation. The permissible values for this card are:
- yes
This value sets the flag WRITE_INITIAL_SOLUTION variable to “TRUE”. The initial solution vector will be written to an EXODUS II file and to an ASCII file (if the number of processors is not greater than DP_PROC_PRINT_LIMIT, currently set to 4 in rf_io.h).
- no
No initial solution is written.
Technical Discussion¶
This option is useful to activate when help is desired in debugging the startup portion of a transient simulation.