Hello, i want to know if it is necessary to precise an operating pressure or a guage pressue to simulate the motion in a cyclone separator with a high mach number (supposition of incompressibility) My other question is that the simulation converge with a low number of cells (10000-35000) by the RSM model, when the mesh is rafined the solution diverge, ho can tell me what's the problem? thanks

For the second question: fine grid can result in numerical instability due to a natural oscillation of the flow (residuals persistently occillating). The problem in known in literature (CSIRO 1997 - Turbulence modelling of single phase flow in a spray dryer).