Improving predictions of transitional and separated flows using RANS modeling

In this paper, new concepts are presented from the aspects of viscous modeling and numerical scheme in an attempt to improve the prediction of rotor hover performance and associated viscous flow physics under a RANS statistic modeling framework. An improved viscous modeling is proposed to address the overprediction of flow separations faced by RANS modeling, which modifies the linear eddy viscosity models based on a new separation correction method. This concept is seamlessly implemented into two popular eddy viscosity models: the Spalart-Allmaras one-equation model and Menter's shear stress transport two-equation model. A new high order unstructured grid WENO scheme is adopted to improve the prediction of mean flow resolutions as well as viscous flow structures around the hovering rotor. Numerical results show significant improvements achieved in the prediction of rotor hover performance as well as viscous flow phenomena including boundary layer transitions and flow separations. (C) 2020 Elsevier Masson SAS. All rights reserved.