Study of limits to the rotation function in the SA-RC turbulence model
Wenhao Li, Yangwei Liu
Abstract
The Rotation and Curvature (RC) correction is an important turbulence model modification approach, and the Spalart-Allmaras model with the RC correction (SA-RC) has been extensively studied and used. As a multiplier of the modelling equation’s production term, the rotation function fr1 should have a cautiously designed value range, but its limit varies in different models and flow solvers. Therefore, the need of restriction is discussed theoretically, and the common range of fr1 is explored in Burgers vortexes. Afterwards, the SA-RC model with different limits is tested numerically. Negative fr1 always appears in the SA-RC model, and the difference between simulation results brought by the limits is not negligible. A lower limit of 0 enhances turbulence production, and therefore the vortex structures are dissipated faster and shrink in size, while an upper limit plays an opposite role. Considering that the lower limit of 0 usually promotes the simulation accuracy and fixes the numerical defect, whereas the upper limit worsens the predictive performance in most cases, it is recommended to limit fr1 non-negative while utilizing the SA-RC model. In addition, the RC-corrected model has a better prediction of the attached flow near curved walls, while the SA-Helicity model largely improves the simulation accuracy of three-dimensional large-scale vortices. The model combining both corrections has the potential to become more adaptive and more accurate.