A Hybrid RANS/KES Model for External and Internal Flow Applications

Abstract

A hybrid RANS/KES (HRKES) turbulence model is proposed for external and internal flow applications. This HRKES model solves Menter’s k-ω-SST model near walls and switches to Kinetic Eddy Simulation (KES) model away from walls. The KES model solves directly for local turbulent kinetic energy and local turbulent length scales, thus alleviating the grid spacing dependency found in other DES and HRLES models. This closure is considered RANS near walls and VLES-LES away from walls. Within the HRKES model, four different options (a combination of two different blending functions and the use of realizability constraints to bound the KES model parameters) have been evaluated and studied for flows over a turbine vane configuration, airfoils (RAE2822, NACA0036), and a compressor configuration. While all four options showed good correlation with the test data, blending k-ω-SST with KES using the k-ω-SST F 2 function showed better predictions in separated flow regions than the baseline k-ω-SST model.