Sorry, Rob. My expression makes you confuse. Therefore, I'm going to describe it again. And then I will answer your questions.nIt's a 2D axisymmetric model using VOF method. The two phases are air and water, and their velocities are -1.052 and 1.19m/s, respectively(counter-current flow). The gravity is in the X-direction. nAnd in the solver, the gravity is defined as follows.nThe operation conditions are shown as follows.nThank you for your help and patience. Looking forward to hearing from you.n