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 Sheila March 11, 2005 07:24

k-w SST model wall conditions

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

 4xF March 11, 2005 15:57

Re: k-w SST model wall conditions

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?

 Sheila March 11, 2005 18:54

Re: k-w SST model wall conditions

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

 Pauli March 11, 2005 19:06

Re: k-w SST model wall conditions

A wild guess - non-equilibrium vs equilibrium wall functions.

 Sheila March 12, 2005 04:55

Re: k-w SST model wall conditions

I am using low Reynolds number version of kw SST.

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