A Two-Equation Subgrid Model for Large-Eddy Simulation of High Reynolds Number Flows

Abstract

A new two-equation Kinetic-Eddy Simulation (KES) model is developed for large-eddy simulation (LES) of wall-bounded high Reynolds number flows. This model solves for the local unresolved kinetic energy and the local length scale. The dissipation of the kinetic energy depends on the length scale, as well as, on the length scale gradient. New terms of subgrid viscous work, subgrid pressure diffusion, and subgrid heat transfer are also proposed for the closure of energy equation. In most of flow domain of simulated cases, the subgrid length scale is compatible to computational grid scale, and KES model behaves like a LES. In some other regions, the length scale tends toward the integral length scales, smoothly approaching very large-eddy simulation (VLES) limit. Thus, this closure is considered a VLES-LES approach. The KES model has been applied for 2D flows around NACA-0015 airfoils at different angles of attack, including regions of linear-lift, mild separation and static stall. The predicted aerodynamics compares well with experimental measurement. Especially in the static stall simulations, vortex shedding with massive separation is clearly captured.