outflow boundar condition problem, mutiphase flow
 

Hello,
I am doing some multiphase flow computations using twoLiquidMixigFoam solver.
Simulation (see attached figure:
Attachment 12791
calculates flow with inflow (emergency valves inflow of the fluid1 to the tunnel filled with fluid2 ) and outfolw from the tunnel.

After fluid1 reaches end of the tunnel a problem appears. Because there is a "recirculation zone" trying to leave the tunnel , imposed boundary conditions does not allow it to leave the computational domain, see attached next 3 figures for different time :
Attachment 12792
Attachment 12793
Attachment 12794
I was trying many different BC for velocity (zeroGradient, InletOutlet, mixedDirections) but result/problem is the same...

Does any one know if there is some simple (or any using proper BC) solution for this problem ? To just allow fluid to leave domain, without doing mass at the outflow ??

Best

interesting is , that after setting (gravity) g = 0, problem disappears ...