Verification of Supersonic Nozzle Flow

Ali Khan

Hello CFD Users,

I am trying to analyse flow through supersonic de-Laval Nozzle at inlet condition of 8 bars, the fluid at present being used is AIR. This gives me an exit Mach No. approx. 2.06, which correlates with the one-dimensional theory. But I am not too sure whether results Y+ values along the expansion section wall is right?

The wall velocity distribution theory suggests that, for a laminar flow Y+ < 11.63 & for a turbulent flow Y+ > 11.63. The result that am getting are Y+ >1<5 for very fine grids near the wall, Y+ >2<10 for medium size grids and Y+ >5<15 for very large grid size.

Is there any CFD user, who has delth with supersonic flow in NOzzles or any of you who know more about this phenomena. Can you please help ?

PS - The turbulent model that I have used for this situation is k-epsilon Realisable, with near wall treatment as Non-Equilibium Wall functions in FLUENT 5.3. Would I be right to use this particular model or through your experience, better model exists. Can you suggest.

Thank you very much for you time and effort

Ali Khan