Dear all

My question is about the boundary conditions in LBM. I want to simulate flow through bearings. The geometry consist of two parallel walls. It is easy !!!!! ... BUT the walls are not smooth and they are mooving with constant velocities.

My question is how to deal with moving irregular boundaries?.

Thanks alot

Ahmad

Hi

Irregular BC is not a problem. If you are not interesting in high order of accuracy, just deal with (full) Bounce Back with 1 order of accuracy. That's all. Otherwise, use half bounce back with 2nd order of accuracy but more computations, as you should know at this point. Regarding moving boundaries, I think, as the first though, you have to use an equation that deal with such "movement". If you are refering to irregular movement, that "equation" should deal with that. Good luck

Cheers Raul

Thank you very much for your answer.

I think you didn't understand the question very well. To apply Bounce back for irregular boundaries is very easy task as you have said. The question is what happen if this boundary is moving... This means that the mesh (grid) will change with time. The problem is if one move it one lattice unit length every lattice time step, this will fix the velocity of the boundary to be 1 and this violate the incompressiblity (u<0.3).

Thank you agian.

Ahmad