I am trying to model a 2D pipe submerged in water using Ansys Fluent . I assigned BC for pipe is porous jump. So I need face permeability (alpha), thickness and C2. I don't understand the alpha term . Then I tried to do as a perforated pipe. Again I face same problem. If I use some default value of Alpha at porous medium, after some run, it looks like attached image. Hope somebody can help me out