Hello,
I am much confused about the boundary layer at the walls of the canal, in the case of a flow around an obstacle.
Can you help me please how to of treat of the boundary layer with LBM? is it necessary to refine the mesh near the walls?
Thank you for help
regards

What type of boundary layer do you mean? A viscous one (e.g., high Reynolds number flows) or a slip one (due to mean free path effects and Knudsen numbers)?

Ok, so that’s going to be a very small Knudsen number, so assume you are interested in viscous boundary layers (unless by less than 300 you mean 1). And you’re looking at flow over an obstacle in an infinite domain, where away from the obstacle the flow is almost Bernoulii? My guess is you’ll beed a lot of mesh refinement along the boundaries, as you say. I remember there being an LGCA paper by Lim about boundary layers.

I work with a 10mm obstacle placed in the middle of a 50 mm channel and I want to know the effect of boundary layer on the instabilities near the wall. The Reynolds number “Re = U * d / nu” . where “d” is the height of the obstacle.