creating an open exit boundary

Hi everyone,

I currently have a working program which has a reflective right hand (exit boundary). I need to try and change this right hand boundary so that it is an open boundary so that the fluid is not reflected back, but simply flows out and the fluid level drops. I have tried various things have not managed to get anything working so far. Does anybody have any ideas or hints that might be able to help me? Any help would be greatly appreciated.

Thanks. James.

Maybe you could have a look at
Michael Junk and Zhaoxia Yang: Outflow boundary conditions for the lattice Boltzmann method; Progress in Comp. Fluid Dyn., Vol. 8, Nos. 1-4, 2008, pp. 38-48