Two methods were applied to improve the capability of predicting separation of Spalart-Allmaras turbulence model.One was to improve the capability of predicting Reynolds normal stress based on the property of Spalart-Allmaras turbulence model

the other one was to calibrate the production coefficient based on the non-equilibrium of turbulence in separation region.The results show that: the first one contributes little to improving the capability of prediction separation of Spalart-Allmaras turbulence model

because the capability of predicting Reynolds normal stresses is not improved considerably;while the second one improves obviously the capability of prediction separation of Spalart-Allmaras turbulence model

because the capability of S-Amodel in capturing the non-equilibrium turbulence is improved notably.