FAQ/Postprocessing

1 FAQ Section 6: Postprocessing

Working with the results

1.1 Postprocessing of Lagrangian particles

1.1.1 Using foamToVTK

This is not yet possible to direcly post-process Lagrangian particles (including droplets) with paraFoam, according to this thread. However, you can work around this limitation by using foamToVTK and Paraview's existing ability to handle point data.

Follow these steps:

1. Run the foamToVTK post-processing utility. As with all OpenFOAM programs, it requires at a minimum, the root and case paths.
2. Read in your Eulerian data, if you wish
3. Read the Lagrangian data separately and 'Glyph' it. Glyphs are how Paraview represents point data. Usually, the sphere glyph is the most appropriate.

The glyphs used to represent particles can be colored and sized to reflect the data associated with the particle. If you cannot see your particles, check that indeed you have represented them as glyphs and that the size scaling you have chosen is adequately large.

1.1.2 Using paraFoam

First you execute paraFoam as usual but you select only in the data to be load the fields and the mesh of the continuous phase.

Then you click on the Open button (or File -> Open in the menu). You select the case.OpenFOAM file created by paraFoam. So you can load again the data of the case. But this time, you select

1. in Mesh Parts the lagrangian clouds (be sure that only lagrangian geometries are selected),
2. in Volume Fields unselect everything
3. in Lagragian Fields select the fields you are interested in.

Then click on the Apply button.

To visualize the particle, use the Glyph filter (cf. end of previous paragraph).

Remark : Test with OpenFOAM-1.6 and ParaView 3.6.1

1.2 Postprocessing of simulations on multiple mesh-regions

Two possibilites to do this are described on How To Postprocess Multiple Regions

1.3 Post-processing multiphase results

OpenFOAM handles multiphase simulations with multiphase flow solver through using a single field that represents the phase present at a certain cell, face or vertex. The field is usually named alpha or alpha1. For more information on how to analyse this field, see this page: How to post-process multiphase results