Questions about the script cylinder.m flow past a cylinder

Hi everyone,

I’m a student working on LBM and i’m new to this method. I have studied the example “cylinder.m” which was very useful as a first example to apply lattice Boltzmann method.
I would like to ask some questions concerning this code and i hope that someone helps me because i’m really struggling with the LBM.

Here are my questions :

  1. Does anyone know the real physical values of the parameters used in this code (velocity at the inlet, viscosity, length …) ?

  2. Concerning the bounce back condition is it half-way or full way?

  3. A simple bounce-back type has provided good results in the code although the geometry of the cylinder could require a special type of bounce back (curved boundary), how?

  4. I have found in some references that on the surface of an obstacle (here a cylinder) we should impose a “zero-flux” boundary treatement, which wasn’t applied in this code i guess. So can we get rid of zero-flux boundary treatement in this case?

  5. There are mentioned “macroscopic dirichlet BC at the inlet” then "microscopic BC at the inlet (Zou & He) . Isn’t Zou & He treatement at the inlet sufficient to impose a dirichlet boundary ? Isn’t it the same ?

Please help me .