Application Setup Guide¶

This page shows common pdeapp.txt setup patterns. Combine these with a matching pdemodel.txt and mesh file.

Steady-State Simulation¶

dt = [0.0];
time = 0.0;
NewtonIter = 20;
NewtonTol = 1e-06;
saveSolFreq = 1;

Run:

/path/to/exasim-prefix/local/bin/text2code pdeapp.txt
cmake -S . -B build -DExasim_DIR=/path/to/exasim-prefix
cmake --build build
build/exasimapp datain/ dataout/out

The exact executable command depends on the app bundle or usage mode.

Time-Dependent Simulation¶

time = 0.0;
dt = [repeat(1e-4, 1000)];
torder = 2;
nstage = 2;
saveSolFreq = 20;

Use saveSolFreq to control saved solution and visualization frequency.

Parameter Sweep¶

physicsparam = [1.4, 0.72, 500.0];
physicsparamcases = [
  1.4, 0.72, 500.0;
  1.4, 0.72, 1000.0;
  1.4, 0.72, 1500.0;
  1.4, 0.72, 2000.0
];
physicsparamwarmstart = 1;

Text2Code writes datain/physicsparamcases.bin. The standalone executable detects that file and runs all cases internally. Output directories follow the same convention as frontend sweeps:

dataout/
  physicsparam_sweep_manifest.txt
  paramcase_0001/
  paramcase_0002/

MPI Run¶

mpiprocs = 4;
platform = "cpu";

Use the MPI-enabled executable and launch it with the system MPI launcher:

mpirun -np 4 build/exasimapp datain/ dataout/out

Text2Code writes rank-local mesh and solution files when mpiprocs > 1.

GPU Run¶

platform = "gpu";
mpiprocs = 1;

Build the generated app with the GPU-enabled Exasim package. The CMake options used by the app select CUDA or HIP, for example -DEXASIM_CUDA=ON or -DEXASIM_HIP=ON when supported by the app CMake project.

Restart-Oriented Configuration¶

Use saved solution files and consistent time-step offsets:

saveSolFreq = 10;
timestepOffset = 1000;
time = 1.0;

Restart workflows depend on the executable/app wrapper used to read prior solution files. Keep datain, dataout, mpiprocs, and mesh partitioning consistent with the saved state.

Postprocessing Workflow¶

Enable derived output:

saveParaview = 1;
nsca = 2;
nvec = 1;
nvqoi = 2;
saveResNorm = 1;

Then run solve mode or explicit postprocess mode if the standalone app supports it:

build/exasimapp postprocess datain/ dataout/out

See Postprocessing for supported command forms and output files.

HPC Setup Checklist¶

Use an installed Exasim prefix visible on compute nodes.
Ensure text2code and generated executables use the same Exasim build.
Match platform to the installed CPU/CUDA/HIP package.
Keep mpiprocs consistent between preprocessing and execution.
Put large dataout/ directories on a filesystem intended for simulation output.
Test with one rank and a coarse mesh before scaling.