A Three-Layer Model for Separated Turbulent Flows

Abstract

A model for turbulent backflows is presented and evaluated. The model is based on experimental observations, in particular, the wake-like behavior of the turbulence and the diffusion/dissipation energy balance observed in detached flow regions. These lead to an ODE for the eddy viscosity, based on a reduced form of the turbulence kinetic energy equation. This ODE is solvable analytically. The model is applied as a module within a “host” eddy viscosity model (such as a k–ε model) using a three-layer framework wherein the host model predicts the eddy viscosity distribution in the inner and outer layers, while the backflow model provides the eddy viscosity field in the middle layer. Predictions of several flow cases, using this approach, are shown.