does someone of you have experience with the Succi Boundary Condition for open boundaries (chapter 6.3)? I didn’t understand it competely. I tried to implement it in the propagation step, but after some timesteps my calculation became instable. First I calculated the density on the nodes one row before the outlet. With this density I calculated the velocity u_temp. Together with the velocity-profile I set at the inlet I calculated the propability r. Finally I multiplied the value r with f0-f8 in case of the last row.
I want to solve the poiseuille flow in a 2 dimensional case (d2q9) between two parallel plates. The problem I have is that the velocity profile at the outlet shows an increase of maybe 10 percent to the one I set at the inlet. This increase of velocity is existing only in the area close to the outlet. I have to say, that I didn’t set any velocity or peridic boundary conditions at the outlet. The intention is to be able to solve the poiseuille flow between non-parallel gaps (convergent gap) later on and to calculate the mass flow.
As always I would be very happy if someone has any ideas which could help me. If you have ideas how to solve the problem another way please let me know.