Assessment of Turbulence Models for Predicting the Interaction Region in a Wall Jet by Reference to LES Solution and Budgets

Abstract

This chapter discusses a study, which assesses turbulence models for predicting the interaction region in a wall jet by reference to large eddy simulation (LES) solution and budgets. Highly resolved LES and experimental data for a plane wall jet are used to study the characteristics of three turbulence models, two based on second-moment closure and the third being a nonlinear eddy-viscosity model. This study started from the premise that a realistic approximation of Reynolds-stress diffusion, only possible within the framework of second-moment closure, was likely to be an important element in modeling correctly the details of the interaction between the outer shear layer and the boundary layer within a wall jet. Comparisons are presented for mean-flow quantities, second moments, and budgets. Also included is an a-priori study of two approximations for the turbulent transport of the Reynolds stresses, a process that contributes substantially to the stress budgets. The study reveals major defects in the closure approximations for the modeled terms in the stress-transport equations, including that for stress diffusion.