[kaaja]

I am running k-omegaSST, and I am really confused about wallfunctions. The more I read about it, the more confused I get. I have some questions I hope someone can help me with:

1) K-omega is meant to be solved without wall-functions, so yPlus should be < 1?

2) omegaWallFunction is really not a wallfunction (it is applied for yPlus < 1, and then wallfunctions should not be used)?

3) If for some reason k-Omega is solved with yPlus > 1, nutLowReWallfunction must be applied?

4) k-OmegaSST is a mix of k-epsilon and k-omega?

5) The idea of kOmegaSST is to use k-omega close to the wall and k-epsilon far from the wall?

6) Since k-omega is used close to the wall in k-omegaSST, one should use omegaWallFunction if yPlus < 1.

7) Since k-omega is used close to the wall in k-omegaSST, one should use nutLowReWallFunction if yPlus > 1.

8) With kOmegaSST and yPlus < 1, what shall one use as wallBC in for Nut?

9) With kOmegaSST and yPlus < 1, what shall one use as wallBC in for k?

10) nutSpladingWallFunction is meant to be used when running kOmegaSST and 30 < yPlus < 200 (the standard wallFunction range I think)?

11) The similarity between nutSpladingWallFunction and nutLowReWallfunction is that both are used for yPlus > 1?

12) The difference between nutSpladingWallFunction and nutLowReWallfunction is that the former is used for kOmega and the latter is used with kOmegaSST?

[Andrew.Coughtrie]

As an example look at the simpleFoam motorBike case in OpenFOAM-1712.

kqRWallFunction for k
omegaWallFunction for omega

Read the following paper which explains the kOmegaSST wall treatment

Esch, T., & Menter, F. R. (2003). Heat Transfer Predictions based on Two-Equation Turbulence Models with Advanced Wall Treatment. In Turbulence, Heat and Mass Transfer 4.

Additionally OpenFOAM now defaults to a switching rather than blended treatment for omegaWallFunction based on improved accuracy at higher y+ values.

Andrew