Restart a Simulation

To restart or continue a simulation, you can either create an additional Engine file or use the checkpoint file.
  1. To use a second Engine file, use the steps described in Multiple Engine Files to create the second Engine file TEST_0002.rad. Start Radioss using second Engine file as the input file and Radioss will continue the job after your stopping point.
    Note: The energy error and mass error start at zero for the second Engine file simulation.
  2. Alternatively, a checkpoint file could be used by following the instructions in Checkpoint File.

Stop Computation and Create RESTART

If a simulation is launched in the Altair Compute Console (ACC) with Solver control options checked, a control file will be created automatically using the STOP option and selecting the Send Command. Otherwise, it is possible to do this by writing a control file in the same directory as the run data. A control file *.ctl must be created that uses the same prefix name as the currently running Engine file. So, if the first Engine is running, a Runname_0001.ctl should be created with the following line in it:

Radioss Engine ends and a RESTART file is written.

The other options available with control files are described in the Control File (C-File) section.

Issue with RESTART file

If the Engine does not start due to a problem with the RESTART file, check that the RESTART file Runname_0000_0000.rst (written by Starter) appears in the directory where Radioss Engine was run. Check for errors in the Starter output file which would prevent the RESTART file from being created.

Create multiple RESTART files during run

To create multiple RESTART files during a simulation, use the option /RFILE/n in the Radioss Engine input file Runname_run#.rad:

Where, n refers to the number of different RESTART files that will be kept. The n RESTART files will generate different names, Runname_0001_cpu#_[i].rst with an extension using a letter: for example, the first RESTART file will be named Runname_0001_0000_I.rst; the second RESTART file will be named Runname_0001_0000_J.rst and so on.

It is possible to write up to 18 different RESTART files within the same run.

For example, if the model is named TEST_0000.rad for Starter and TEST_0001.rad for Engine.

First, in your Engine file TEST_0001.rad you should define /RFILE/n. For example, if you want to create 6 RESTART files every 500 cycles, then include the following:
Then in your current folder, you may have the following restart files depending on your model:
Note: The file name always begins with Restart Letter=I. So, here it begins with TEST_0001_0001_I.rst.

Now to continue your job using the “K” restart file, the second Engine file TEST_0002.rad should be created. In this Engine file, you must assign the keyword /RUN.

For example:

Now launch this second Engine file, Radioss will continue the job after the point of TEST_0001_0001_K.rst.