# some quiries about how to set a "low_Re" kOmegaSST model?

 Register Blogs Members List Search Today's Posts Mark Forums Read

 May 5, 2013, 12:13 some quiries about how to set a "low_Re" kOmegaSST model? #1 Senior Member     Ehsan Join Date: Oct 2012 Location: Iran Posts: 2,210 Rep Power: 19 Sponsored Links I want to have a turbulent kOmegaSST model with yplus<=1 to be sure that separation regions and adverse pressure gradients are calculated and included truely not through some "wall-function rough estimations". he has a low-Re grid mesh. 1)is my approach(stablishment of a very fine mesh near the wall to capture precisely separation and adverse pressure gradients there) true? 2)how have to set kOmegaSST to have a low-Re model satisfies 1? 3)I then need "y plus" to be certain that mesh is fine near wall with y+<=1 and only "y plus" not "y star" or any other thing instead of "y plus" (yPlusRAS tool calculates y-star based on wall-functions). __________________ Injustice Anywhere is a Threat for Justice Everywhere.Martin Luther King. To Be or Not To Be,Thats the Question! The Only Stupid Question Is the One that Goes Unasked.

 May 6, 2013, 03:44 #2 Member   Ignacio Join Date: Jan 2013 Posts: 31 Rep Power: 6 Hello Ehsan, 1) Yes, Low Reynolds kOmegaSST model includes a set of damping factors and constants that make it possible to use to integrate through the boundary layer. It doesn't need wall functions. 2) You need to define patches for k, omega and mut (compressible) / nut (incompressible) k --> fixedValue, uniform 1e-10 mut/nut -- > compressible::mutLowReWallFunction, uniform 0 omega --> compressible:megaWallFunction, uniform 0 3) yPlusRAS in OpenFOAM does not calculate the yPlus for Low Re. It uses a correlation for the friction coefficient which is only valid for high Reynolds numbers. You will need to extract the velocity data at the first cell in the boundary layer and calculate it by yourself (approximate the derivatives in the wall shear stress to small increments) immortality, hello-CFD and stingph like this.

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post vijay2049 FLOW-3D 0 February 20, 2013 13:16 sh.d OpenFOAM Programming & Development 3 October 14, 2012 07:57 FelixL OpenFOAM Bugs 27 March 27, 2012 09:02 dutliang FLUENT 3 December 13, 2011 22:28 richard2000 CFX 3 September 14, 2010 03:04