SpalartAllmaras boundary condition
I have a few questions about SpalartAllmaras model, I applied it to an airfoil (blade section of a marine propeller).
1. I guess a turbulent viscosity ratio equal to 1, so nut = nu. I don't find a shared opinion about nuTilda: nuTilda = 3 * nu? nuTilda = 5 * nu? Maybe it's not so important. 2. Wich is the best range for y+? 3. My reference case is 2DAirfoil tutorial (incompressible/simpleFoam). I don't know the meaning of freestreamPressure or freestream BC types, I've used fieldValue or zeroGradient so far. Could you explain this to me? For istance, I used (kw SST model): inlet: p = zeroGradient; U = uniform (7.30 0 0); k = uniform 0.24; omega = uniform 1.78 outlet: p = uniform 0; U = zeroGradient; k = zeroGradient; omega = zeroGradient; wall: p = zeroGradient; U = uniform (0 0 0); k = uniform 0.24; type: kqRWallFunction; omega = uniform 1.78; type: kqRWallFunction; side: p,U,k,omega = symmetryPlane; frontAndBack: p,U,k,omega = empty; Thanks for your help (and patience). 

Hi !
I really don't understand how to set the BC for the Spalart model either. What I read in the litterature explains that it is suitable to choose something between 3*nu and 5*nu. On the wiki, you can also find a formula which depends on the turbulent length scale and the turbulence intensity. When I apply it for a cylinder in a wind tunnel of turbulence intensity of 1%, a turbulence length scale of 0.11m (estimated with the dimensions of the wind tunnel used by Roschko), and for a velocity of 15 m/s, I have nutilda/nu >> 5 Conclusion 1: my flow, is not fully turbulent... But lets make it more turbulent : we will have to increase velocity. But if we increase it, nutilda is going to increase, and never come closer to 5*nu Conclusion 2 : there is something I don't understand on the way you choose the Spalart BC. If anyone has an idea, I would be very delighted to hear it ! thanks in advance ! 
All times are GMT 4. The time now is 17:31. 