ON THE RELIABILITY OF REYNOLDS-AVERAGED NAVIER STOKES PREDICTION OF MEAN FLOW CHARACTERISTICS OF A RECTANGULAR TURBULENT JET IN CROSSFLOW

Abstract

A jet of fluid discharging into a cross stream, also known as Jet In Crossflow (JICF), has received many experimental and numerical investigations. In addition to the fundamental understanding of three-dimensional mixing and shear flow characteristics, the fluid dynamics research community often regarded it as a benchmark test case for validating turbulence models. Although many authors considered the canonical case of a jet issuing from a circular orifice, the rectangular shape has received less numerical investigations. The present study deals with a jet issuing from a rectangular duct into a confined crossflow domain in which five jet-to-crossflow velocity ratios ranging from 3.3 to 10 are considered. The analysis focuses on the reliability of three two-equation turbulence models, namely k-ϵ, k-ω and SST in predicting this type of complex flow phenomena. Comparisons with previous large-eddy simulation results and available test data for the same problem have revealed good agreement in predicting 'mean' flow properties, but relative poor agreement in predicting the second-order statistics. It indicates that this type of flow exhibits significant non-equilibrium behavior for which the commonly used two-equation turbulence models are unable to deal with. Thus it is necessary to apply anisotropic turbulence model such as Reynolds stress model or high-fidelity large-eddy simulation method.