Investigation and Modification of Spalart-allmaras Turbulence Model and Its Application to Flow Over a NACA 0012 Airfoil

In this paper, the full two-dimensional Navier–Stokes equations in the external turbulent flow were numerically modeled. Thus, in order to calculate the fluxes, the Ausm method was utilized and for modeling turbulent flows, the single-equation Spalart-Allmaras model was used. The employed Spalart-Allmaras model is a modification of this turbulence model, which prevents the formation of negative dynamic viscosity, a point that has gone generally unnoticed. The suggested modification was conducted on the distributing and the source terms in the single equation of turbulence model. For validation and assessment of accuracy and stability of the turbulence model and the calculation method of fluxes, the totally turbulent flow with Reynolds number of 9106 and Mach number of 0.799 and angle of attack 2.26 and also flow with Reynolds numbers of 6106 and and Mach number of 0.15 and angles of attack zero,10 around NACA 0012 airfoil are investigate. The results of this study show that computational framework designed have a good agreement with experimental data .furthermore the number of iterations required for convergence is reduced.