[lershbersh]

Hello everyone,


I am a student from Germany trying to simulate the flowfield inside a spiral Jet Mill using STar CCM+. The problem I face is, that the calculated Gas velocity throug th inlet nozzle is far beyond the sonic speed of ~350 m/s for the given fluid (Nitrogen). I use a mass flow inlet. With the used mass flow I should get around 320 m/s.I use periodic boundarys since the mill has rotation symmetry.



For meshing I use the polyhedral volume mesh, the prism layer mesh and a volumetric mesh control for the nozzle area. I have close to a million cells, wich i thought should suite the purpose well enough. (Some papers used around 300k)


The used solver is the steady state coupled implicit solver with the ausm+ scheme.


The velocity calculation should be limited to the sonic speed for compressible flows. This is written in the Sim Center Documentation.


I would really appreciate some help

Thanks to everyone who takes the time to give me some advice. Best regards
Leo