wish: directed pressureBoundary creation from any Box3D


I want to read the pressureBoundaries from STL files (because that enables me to place them via blender), and for that I need a function which can take any Box3D (with direction like function2N) and make the outer face in the given direction a pressure boundary and the rest simply bounce back nodes.

Could you add a function like that? (or does it already exist and I just haven’t found it?)

It would make it much easier to define simulation setups, even going as far as writing a simularion once and then getting the lattice and the boundaries from STL files passed via the commandline.

Best wishes,


No, this is currently not implemented in Palabos. The reason why we hesitate, as of now, to implement the possibility of reading the location of inlet/outlet nodes from the STL is the following. Inlet/outlet nodes are currently implemented through boundary conditions (Zou/He, regularized or others) which must necessarily be aligned on a plane. It is difficult (and error prone) to ensure that this condition will be met by general data read from the STL. For this reason, we prefer to create the inlets and outlets manually in the code.

General boundary conditions which don’t need to be aligned with the computational grid are part of current development efforts in Palabos. Once this is done we will certainly orient our efforts towards more general input capabilities from STL or other CAD formats.

If you’d like to implement this yourself, you will probably have to touch the code of the CVMLCPP library which Palabos uses to voxelize the fluid domain.

Is it already possible to get positioned and correctly scald data from STL?

I have code in place to cut the domains from STL files into a plane and a shortened cube behind it, so I can just create simple cubes in blender from which I then take one front as outlet.

But a cube automatically gets scaled to the whole simulation, making every lattice node a bounceback. If I could just supply the scaling and positioning from one import (main STL) to another one (outlets) I could get the outlets from STL files with cubes (if it isn’t cubes, I get too many domains :slight_smile: ).