Orifice

Juan Martin Catelén

Hi. I made some question before about the same problem. I have a restriction orifice in a pipe and I want to have a loss of 4.5 bar. The discharge is at atmospheric pressure. I want to see if there is cavitation. I have followed the Best practices for cavitation and I have some problems. First, I was getting a flow higher than the one I got with other reliable programs (non cfd). Then by changing the mesh the result wasn't changing (I was running it in steady State and without cavitation at the beginning, and then in transient to get better results) until I started to use inflation. I was trying to get the expected result in the flow value or pressure loss (with cavitation model off and out of the region of cavitation) and also to get a mesh independent result, but how can I be sure that with another type of mesh the result won't change? Shoul I use ICEM with hexaedra (I know that if better for this type of problem but I still don´t know how to use the ICEM)? I'm sure that the geometry and the boundary conditions are correct, so if this is a numerical problem, what shoul I do? I have attached an image of the mesh. It has inflation on the orifice (5 layers). Thanks in advance.