Wall BC's for a NS solver

André Burdet

Hi there,

I am currently writing a 3D unsteady Navier-Stokes solver using the FVM and Lax-Wendroff scheme (1 step) for the time integration. I have a problem to implement the no-slip BC's, at least to correct the viscous flux. The algorithm is the type of node-based so that I have the state variables stored in the nodes of each cells. The shear stress is then evaluate in the mid-cell edges and contribute to each surrounding nodes. Concerning the wall boundary treatment, I put a dummy cell row inside the wall where each nodes contains a negative velocity corresponding to the real one inside the real flow domain. This dummy cell row contribute to the correction of fluxes for the next time step state values in the vertex nodes of the cells attach to the wall. When the code is run, the divergence appears quite quickly. Actually, It is seen that there is oscillation of pressure then velocity at the wall (like odd-even case ...) Has anyone of you an idea why I am facing this problem (I have already a numerical smoothing) and also how handle the wall BC's with the method I use.

Cheers.