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Old   February 20, 2009, 23:29
Default Constant value in SA model
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How does making ammendment in the constants of the SA model improve my Cd results ??? By decreasing, it take very long to converge yest its not nearer to my experimental results. By increasing the constant, i will get a lot of reversed flow...

Please help!!!!! i really cannot understand....

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Old   February 22, 2009, 09:50
Default Re: Constant value in SA model
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Are you talking about S-A model constants or under relaxation factors. It is not necessary to amend the model constants. For convergence issue decrease the under relaxation factors. What ever the case may be if you are simulating low Re flow then the drag value will be too high. Try to set a small value i.e. 1e-3 or less for turbulent viscosity ratio in the velocity inlet boundary condition. This will solve the reverse flow. Check the previous weeks post, there was some discussions about the Cd.

Cheers, Alagesan.
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Old   February 23, 2009, 00:38
Default Re: Constant value in SA model
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hey thanks a lot.. but i do change my turbulent viscosity in the inlet boundary solution( until to 0.05) but it still varies a lot for the drag value experimental results.

Although i had use High Re no like 2miilion SA model to test for results if it still wont get nearer to experimental drag results Is there any thing goes wrong??? Does refernce values affect the simulation>??

Pls help??
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