Reply To: add gravity leads to instability, bifurcation 3D, multiphase, particles

[Manuel Berger]

Dear Mathias!

Thanks for the fast response and the hints:

1/ I have used the converter to convert quantities into lattice units (i.e. gravitation code line 174)

T gLB= gravity*converter.getPhysDeltaT()*converter.getPhysDeltaT()/converter.getPhysDeltaX();

I have also used the poiseuilleXd file as a starting point. However, it shows how to apply a body force, but not how the body force is connected to gravitation. I think in the LB framework OpenLB, there is so far no code that shows this connection. The LB framework palabos (palabos-v2.0r0\examples\showCases\vofMultiPhase\damBreak3d.cpp) shows that body force and gravitation (in lattice units) is the same. Code line 70,71. I assume my implementation of gravitation is fine in the bifurcation3d (see dropbox)?

2/ You are right Buoyancy forces are not considered.

3/ I get already a stable simulation result with changed boundary conditions (without gravitation). Adding gravity (1 thing changed) does not work.

I would be great if you could find a specific mistake in my code or recommendation i could change.

Thanks you very much for the help in advance

Manuel Berger