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-   -   how to define the symmetric boundary condition for Menter's SST turbulence model? (http://www.cfd-online.com/Forums/main/109626-how-define-symmetric-boundary-condition-menters-sst-turbulence-model.html)

 flyingseed November 22, 2012 05:05

how to define the symmetric boundary condition for Menter's SST turbulence model?

hello,

I am using Menter's SST turbulence model in the turbulent plate case described in http://turbmodels.larc.nasa.gov/flatplate.html.
How should I define the boundary condition at the symmetric part before the flat plane.

thanks,
flyingseed

 Far November 22, 2012 06:38

Use wall condition with zero shear.

 flyingseed November 22, 2012 08:16

In process of solving the NS equations, it is OK that the no shear wall boundary condition can be applied.
But in turbulent models, the variables are 'k' and 'omega', how can I define the no shear wall boundary?
could you explain it more clearly?

flyingseed

 Far November 22, 2012 08:19

which solver you are using?

 flyingseed November 22, 2012 08:33

you mean NS equations part? WENO5 for convective terms and 2nd center scheme for viscous terms.
And for turbulent models, 1st upwind scheme for convective terms and 2nd center scheme for diffusion terms.

Thanks
flyingseed

 Far November 22, 2012 09:06

Apply the wall boundary condition at the part of wall with zero shear (slip). Treat the plate as no slip boundary

 flyingseed November 22, 2012 09:59

yes, I did as you said in solving the NS. When solving the laminar plate, I got good results compared with the Blasius solution.

But when I turn on the turbulence model, the eddy viscosity(turbulent viscosity) is somewhat smaller than the results given in the nasa website. After checking every part of turbulence model, I found the symmetric boundary conditions before the plate for the turbulence model equations had very previous effects on the turbulent viscosity.

So I am wondering which boundary condition should I adopt?

thanks,
flyingseed

 flotus1 November 23, 2012 09:45

A symmety boundary condition is applied by setting the wall-normal gradient of the variables to zero.

 flyingseed November 24, 2012 03:53

thank you. I am trying this way. hope it works.

flyingseed

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