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justindhy April 3, 2006 13:19

pressure coefficient
Dear friends,

After solution was converged and y+ < 400, the pressure coefficent was still larger than what I expected when just setting the free stream velocity at the inlet boundary as reference velocity. Now the result is 1.26, but in thetheory, it should be 0.7~0.9.

Could you tell me what the problem is?

Thanks in advance, Justin

CFD Guru April 4, 2006 13:30

Re: pressure coefficient
What is tubulence model? What is the kind of near wall treatment you are using? What is the geometry? Is there flow separation taking place? If yes, then limit the y+ and bing it below 150 or so.

Use enhanced wall function approach and then report the results again.

justindhy April 5, 2006 06:43

Re: pressure coefficient
Thanks. Now I am studying wind environemnt around buildings. The used turbulence model and wall function are rng k-eps and standard funaction. the domain and model are boxes. The separation really occured. The problem is that if I set the lower y+ max allowed, the size of cas and dat files will increase from 150Mb to 800Mb and it will affect the speed of calculation. Can I just make the y+ of near the model wall lower than 150 and keep the other wall about 400?

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