CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   STAR-CCM+ (http://www.cfd-online.com/Forums/star-ccm/)
-   -   Wall treatment - RSM turbulence model (http://www.cfd-online.com/Forums/star-ccm/106822-wall-treatment-rsm-turbulence-model.html)

djack September 10, 2012 05:34

Wall treatment - RSM turbulence model
 
Hi guys,
I'm modelling a cold chamber with Star CCM+ using RSM turbulence model.
With this turbulence model, Star CCM automatically select the high y+ wall treatment because RSM model is more valid when near wall cells are located in the log law region (high y+ value).
However my question is, what's happening when the y+ value falls below the recommanded minimal value (12).
I've read that in Fluent an hybrid wall treatment is available which switch automatically the resolution depending on the y+ value when y+ is above or below 11.225.
Is Star CCM doing the same even if the high y+ wall treatment is selected ?
Thanks,
Djack

abdul099 September 12, 2012 10:51

Quote:

Originally Posted by djack (Post 381019)
I've read that in Fluent an hybrid wall treatment is available which switch automatically the resolution depending on the y+ value when y+ is above or below 11.225.
Is Star CCM doing the same even if the high y+ wall treatment is selected ?

I don't think so. But you might uncheck "Auto-select recommended models" and choose "Linear Pressure Strain Two-Layer" instead of "Linear Pressure Strain". Then you will have a All-Y+ Wall Treatment available. Please have a look in the user guide, there's an explanation what the All-Y+ wall treatment does:

Quote:

The All y+ Wall Treatment makes no assumption about how well the viscous sublayer is resolved. By using a blended wall law to estimate shear stress, the result will be similar to the Low y+ wall treatment if the mesh is fine enough. If the mesh is coarse enough (y+ > 30), the wall law is equivalent to a logarithmic profile.


All times are GMT -4. The time now is 17:00.