Reply To: Gas-liquid turbulent flows with LBM
Unfortunately I am not using the Shan-Chen pseudo potential method, but another approach to multiphase modelling based on the free-surface VOF model by Thürey et al. (you may find it here) which simulates and couples both gas and liquid phases.
As Max has said, implementing pressure boundary conditions for the Shan-Chen multiphase (or multicomponent) model is not easy. The reason is that the Shan-Chen equation of state is as follows:
p = cs2*(rho + dt^2*G*psi(rho)^2/2).
whereas many ‘standard’ LBM schemes have the ideal gas EOS, namely:
p = cs2*rho
OpenLB implements pressure BCs by imposing density, thus assuming that the model’s EOS is the ideal gas one. I have not found any articles that present an acceptable pressure outlet BC for the Shan-Chen model, so I would recommend doing as Max suggests.
Here is an interesting idea by Timm Krüger regarding how to implement an inlet boundary condition in the Shan-Chen model.
Please note that, although I know pseudo-potential models and have worked with them, I am not an expert in LBM. Anyway let me know if you have any other questions and I will try to help.