Accumulation of gas at channel outlet
 

Hello everyone,



I am running a simulation of a narrow channel consisting of a fluid that is a mixture of gas and liquid. I am using the interFOAM solver for this. At the end of 1s of simulation I am observing a weird accumulation of gas at the outlet. I have attached the image of the issue and the mesh. I feel this accumulation is not physical and is causing disruption of the flow upstream. I have also attached the boundary conditions at the outlet for U, p_rgh and alpha.water here.



Outlet
U :

type inletOutlet;
inletValue uniform (0 0 0);

p_rgh:
type totalPressure;
p0 uniform 0;


alpha.water:
type zeroGradient;


I am trying to get a venting to atmosphere condition here. I also tried a zero gradient outlet condition but it too resulted in the same.