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Ershath November 13, 2010 12:39

Supersonic Inlets
 
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hi,
Am using fluent to simulate a external compression inlet in which a terminating normal shock should appear at the cowl lip which am not able to get. Initially i thought my design was wrong. But once i tried to simulate a design from a literature.Its a experimental work, still was not able to get the normal shock at the cowl lip. Now i have a doubt that my boundary conditions or the procedure am following might be wrong. Kindly go thru the attached file. At the inlets exit i hav given pressure outlet as boundary. When i went thru the help files,it says that the fluent ignores the pressure outlet boundary condition if the flow is locally supersonic. Is that the problem in my case? As far as my understanding goes the solver should capture a shock based on the flow phenomenon. The flow after the normal shock and the position of the normal shock only will be affected by the exit boundary condition. Also i wanted to know how do i impose back pressure.

I use density based coupled solver, ROE ,Second order upwind scheme.
Solution converges up to 10e-3 (i monitor mass flow rate at exit it remains constant when the solution converges) without any problem but does not converge beyond tat. if i do pressure gradient based grid adaption the residues reduce up to 10e-1 and the solution starts diverging or remains constant

Thanks
Ershath


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