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-   -   Wall functions vs. Solving viscous layer (https://www.cfd-online.com/Forums/openfoam-pre-processing/226470-wall-functions-vs-solving-viscous-layer.html)

TommyM April 28, 2020 17:14
Wall functions vs. Solving viscous layer
 
Hi All,

I am trying to simulate the flow in a supersonic nozzle where a shock wave occurs.
I have already run a simulation in conditions of viscous turbulent (k-omega SST model) flow, where I have used wall functions.
Today I have found that the wall functions can be used only if 30< yPlus < 300, and I have yPlus = 0.02.

Strategy 1 - Wall Functions:
If I lower the mesh refinement in order to increase the yPlus value to 30, then there is not mesh grading at the wall and the numerical grid is uniform (it seems strange to me).

Strategy 2 - Solve viscous sub-layer:
I could retain the mesh (as yPlus < 1) and I must not use wall functions. But, which wall boundary conditions should I use for k , omega?

If someone could give me some hints, I would really appreciate.
Tommy


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