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k-w SST model wall conditions

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Old   March 11, 2005, 07:24
Default k-w SST model wall conditions
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Sheila
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Hello everyone,

I am writing my own code for SST model and comparing the data with that given by STAR. Frustratingly enough, I cant match them. Acording to the manuel and STARs data, the w and viscosity of the near wall cell is fixed. When I carry out my calculation, it seems like the near wall k value is very small compared to that given by STAR. And also, the vorticity is VERY small relative to STARS value. From this I deduced that STAR is using some kind of WALL treatment which is not mentioined in the manuels. I wonder if anyone knows what that is or can direct me in the right direction.
My velocities along y direction are similar to that of STAR, so I dont see how near wall vorticity can be so different. Please help....

Sheila
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Old   March 11, 2005, 15:57
Default Re: k-w SST model wall conditions
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4xF
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As far as I understood, omega is not the vorticity, but rather the specific dissipation rate which has the dimension of a frequency... Are we talking about the same?
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Old   March 11, 2005, 18:54
Default Re: k-w SST model wall conditions
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Sheila
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Hi 4xF, yeh, you are right, w is the dissipation rate, which is fixed for the near wall cell. Vorticity, or rather the magnitude of vorticity comes into action in the equation for the turbulent viscosity. Thats why I have it in my data file. I used the VELGRD to calculate the velocity gradients from which I can calculate the vorticity.
Any idea on the wall condition or anything why the results dont match? I am pretty sure my implementation is correct. I have also checked it with someone with high authority in CFD.

Thanks. Sheila
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Old   March 11, 2005, 19:06
Default Re: k-w SST model wall conditions
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Pauli
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A wild guess - non-equilibrium vs equilibrium wall functions.
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Old   March 12, 2005, 04:55
Default Re: k-w SST model wall conditions
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Sheila
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I am using low Reynolds number version of kw SST.
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