Restart File Output and Control
STEADY STATE RUNS:
For steady-state runs, restart files can be written periodically at selected intervals for checkpointing purposes. The optional parameter NCYC_CHECKPT (See Utility Code Reference) is used to control this feature.
When a non-zero value of NCYC_CHECKPT is specified in the input parameter file, a solution restart directory named restart.# is written out every NCYC_CHECKPT iterations. The # in the restart.# directory name consists of a 6 digit integer referring to the iteration number of this run at which the solution restart directory was created. This number includes all iterations run on coarser grid levels using the MMESH parameter in the current run, and thus may not correspond to the fine grid iteration number. Additionally, the restart checkpointing feature is only active on the finest/last grid of the MMESH sequence.
Using the NCYC_CHECKPT parameter, multiple restart.# directories will be written out during a typical run, and these will be written to the current working directory (./WRK). At the end of the run, a final restart.out and restart.aux.out directories will also be written to the working directory (./WRK). Note that the auxiliary variables found in restart.aux.out are only written out at the end of the run and are not affected by the value of NCYC_CHECKPT.
For unsteady or time-dependent runs, there are two possible checkpointing output directories. The first is the restart.# directories, which are controlled by the NCYC_CHECKPT parameter set in the input parameter file for NSU3D. However, in this case, the value of NCYC_CHECKPT refers to the time step number and the restart.# directories will be output every NCYC_CHECKPT time steps (as opposed to iterations or sub-iterations), and the # number on the directory name refers to the time step value. At the end of the entire time-dependent run, a final restart.out and restart.aux.out directories are written to the current working directory (./WRK). Note that the auxiliary variables found in restart.aux.out are only written out at the end of the run and are not affected by the value of NCYC_CHECKPT.
An additional set of solution directories can also be written out during a time-dependent run. These directories, labeled solution.# consist of a reduced set of information which cannot be used to restart the solution process, but which is sufficient for visualizing the solution using standard visualization tools, and for making animations. These files may be useful for constructing time dependent animations where many solution instances are required because they typically contain less data than the complete restart directories. Output of the solution.# directories is controlled by the NTIME_STEP_OUT parameter specified in the input parameter list for NSU3D, which is a mandatory parameter to be included for time dependent runs. During a time dependent run, solution.# directories will be written to the current working directory (./WRK) every NTIME_STEP_OUT time steps, and the # character represents a six digit value of the time step at which the solution file was created. A final solution.# file is not necessarily produced at the end of the unsteady run. In order to guarantee the output of a solution.# directory at the final time step the total number of time steps should be evenly divisible by NTIME_STEP_OUT.
Values of NTIME_STEP_OUT equal to 0 or negative values will omit all solution.# output.
NOTE: Solution files do not contain any history information or logs.