6. Post-Processing

The PI-DSMC Software package relies on third party visualization tools for post-processing. PI-DSMC contains a program called PIDSMCoutput that converts the sampled flow filed quantities to different file formats. The table below lists the available command line parameters for PIDSMCoutut.

name required / optional description
-d directoryrequiredDefine the working directory.
-hoptionalShow the help screen.
-s xoptionalOutput every x-th value in order to reduce the resolution and the file size.
-points fileoptionalDefine a list of points.
-format xoptionalSet the output format. 1: flow VTK, 2: flow MAT, 3: flow PLT, 4: surface text, 5: surface Tecplot text, 6: points text
-species xoptionalSet the species. 0: gas mixture, x: species x
-quantities xoptionalSet the quantities. 1: all, 2: single, 3: all in individual files, 4: physical quantities only
-qmoptionalSame as -quantities 4
-dat xoptionalSet the quantity for output. Value must be determined from the menu.
-file nameoptionalSet the name of the output file. Extension will be added automatically.
-rawoptionalGenerate raw files instead of vtk files.

After PIDSMCoutput was started, a menu will display the available options. Currently, the following file formats are supported:
  1. .vtk - These binary files can be used with ParaView1 (free of charge).
  2. .mat - These binary files can be used in MATLAB2.
  3. .plt - These binary files can be used in Tecplot3.
After selecting the file format, the gas species for which the flow field quantities should be written can be selected.

Finally, the flow field quantity can be selected.

6.1 Quality criterion

The quality of a DSMC calculation can be judged by the ratio of the local mean separation of the collision partners to the mean free path (mcs/mfp). For a good DSMC calculation this ratio should be less than 1/3 throughout the flow. The mcs/mfp ratio can be reduced by using more molecules.