[om3ro]

I need to simulate several different configurations by changing a geometrical parameter, so I would like to change just the value of a constant instead of changing all the points of the mesh:

A simple example of what i need:

int b;
b=4; // b can vary from 2 to 6 : 2, 2.1, 2.2, 2.3, ... , 5.9, 6.

vertices
(
(0 -1 0)
(b -1 0)
(b 0 0)
(0 0 0)
(0 -1 1)
(b -1 1)
(b 0 1)
(0 0 1)
);

Is it possible to make that?

Regards
Marco

[pg22]

The m4 pre-processor is handy for this sort of thing. You define the constants in a separate file, blockMeshDict.m4 say, and use m4 to do any necessary calculations and write out a new blockMeshDict file.

There are some examples in the forum and also on the wiki (e.g. OSIG)

[olesen]

Originally Posted by pg22

The m4 pre-processor is handy for this sort of thing. You define the constants in a separate file, blockMeshDict.m4 say, and use m4 to do any necessary calculations and write out a new blockMeshDict file.

There are some examples in the forum and also on the wiki (e.g. OSIG)

Indeed m4 is the most reasonable approach at the moment.
The dictionary $variable expansions will generally not work, since the blockMeshDict entries are mostly read as straight lists.

However, you don't need to look any further than some of the tutorial examples.

$ git ls-files | grep m4

yields this list of files:

tutorials/compressible/rhoPimpleFoam/angledDuct/constant/polyMesh/blockMeshDict.m4
tutorials/compressible/rhoPorousSimpleFoam/angledDuctImplicit/constant/polyMesh/blockMeshDict.m4
tutorials/incompressible/MRFSimpleFoam/mixerVessel2D/constant/polyMesh/blockMeshDict.m4
tutorials/incompressible/porousSimpleFoam/angledDuctImplicit/constant/polyMesh/blockMeshDict.m4
tutorials/multiphase/interDyMFoam/ras/sloshingTank2D/constant/polyMesh/blockMeshDict.m4
tutorials/multiphase/interDyMFoam/ras/sloshingTank2D3DoF/constant/polyMesh/blockMeshDict.m4
tutorials/multiphase/interDyMFoam/ras/sloshingTank3D/constant/polyMesh/blockMeshDict.m4
tutorials/multiphase/interDyMFoam/ras/sloshingTank3D3DoF/constant/polyMesh/blockMeshDict.m4
tutorials/multiphase/interDyMFoam/ras/sloshingTank3D6DoF/constant/polyMesh/blockMeshDict.m4
tutorials/multiphase/interFoam/MRFInterFoam/mixerVessel2D/constant/polyMesh/blockMeshDict.m4