need info regarding time step for turbulence mode

prashant

Hi,

I am doing PhD in IITKanpur, I am trying to use the Spallart-Allarmas turbulence model for flow past NACA0012 Airfoil.

We are using FEM for CFD. Governing Equations are solved using the Galerkin formulation with SUPG and PSPG stabilisation terms.

For low angles of attack (0.5,10,11) it supports 10e-04, but as the angle of attack increase (12,12.5,15....) it supports still lower time steps like 10e-05 and above.

I want know the

1. WHAT IS THE OPTIMAL TIME STEP FOR THE GENERAL TURBULENCE MODEL like Baldwin-Lomax, Spallart-Allarmas for 2D & 3D Problems?

Thanks in Advance Regards, Prashant