I am simulating a 3D airfoil at Reynold's numbers of 10e5 . I am using Spalart Allmaras Turbulence model . I was wondering what value of Y+ I must use while using SA model .
For some turbulence models in FLUENT (I assume you use this software as seen in the keywords of the post) you can also activate near wall treatments that give you some flexibility to deal with y+ and, obviously, the mesh near the wall. However, your application may require a y+ < 1 because of the potential effect on the vortex shredding. I encourage you to try different options and turbulence models and compare.
It is relevant to estimate the non-dimensional wall y+ to be suitable selection criterion for determining the appropriate mesh configuration and turbulence model, coupled with near wall treatment, that lead to accurate computational predictions.However for better results the grid must be modify so the centroid of the near wall cells does not lay in the region of 5< y+