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-   -   wall functions and boundary conditions in OF 1.7.1 (http://www.cfd-online.com/Forums/openfoam/87990-wall-functions-boundary-conditions-1-7-1-a.html)

cristobal May 4, 2011 20:27

wall functions and boundary conditions in OF 1.7.1
 
Hi everyone,
I am running a case of flow past an airfoil using simleFoam and the kOmegaSST turbulence model. I have a y+ of less than 1 everywhere. When I use wall functions it runs ok, but it doesn't quite reach the free stream value of k that I specified in the boundary conditions. When I use the FixedValue condition at the wall, the boundary layer gets way too thick. I am not sure what the value of omega should be at the wall, in theory it should be 0, because k=0, but when I specify that value the solver crashes. I tried a very small but non-zero value and it runs, but with the BL grows too thick.
I am not sure if using wall functions is justified if y+ is less than 1, can anyone give me some advice?

Cheers.

The King May 5, 2011 10:50

Wall functions
 
For turbulance, there are two methods close to the wall. Wall functions for y+ > 30 or integrating to the wall. See

http://www.cfd-online.com/Wiki/Near-...k-omega_models

Good luck!

romant May 6, 2011 04:10

if you wanna run this case in low Re approach, consider the following link http://www.cfd-online.com/Forums/ope...omega-sst.html it will give you the right boundary conditions and some suggestions on how to use the OpenFOAM kOmegaSST model in a low Re (y+<1)


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