Dear Friends I am simulating a rectangular bubble column(using MPPICFoam) and I want to refine the mesh as small as possible in Y-direction. One thing in unknown to me; How momentum distribute in cells? Do we have force distribution just in One cell? or the code distributes to the neighboring cells too? As you can see from the attached figure, the code diverges when it reaches to finer mesh, and I think it happens because only one cell absorbs all momentum and do not distribute it to the neighboring cells. Am I right? What is your suggestions?