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How does CFL number and wall roughness affect the solution?

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Old   January 22, 2017, 08:04
Default How does CFL number and wall roughness affect the solution?
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Prem Sagar
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I'm simulating a compressible flow in a diverging duct. With a CFL number of 10, the shock keeps moving upstream of the duct with more iterations. But it never stops! It moves way upstream as compared to my experimental values. The residual plots almost saturate at some point as the shock is moving. So is it admissible to stop my iterations once the shock reaches the experimental location?
(Having played around with the CFL number, I observed that it took forever for the shock to move upstream to the required location for CFL=5)

At some point I figured may be the wall roughness had a role to play, but after trying different values for wall roughness the shock still moved upstream.

Im using the SST model, implicit scheme, AUSM flux splitting

Any suggestions would be appreciated
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cfl number, compressible flow, shock wave, wall roughness

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