Management of a Stronger Wall Jet by an Embedded Streamwise Vortex : Reynolds Stresses Distributions and Evaluation of the Vorticity Transport Equation

Abstract

An experimental study was carried out on the Reynolds stress distributions and production terms involved in the vorticity transport equation in a three-dimensional turbulence field of a stronger wall jet managed by an embedded streamwise vortex. Even in the strong three-dimensional flow field the mean velocity gradients 〓U / 〓y and 〓U / 〓z are of primary importance to the quantitative feature of the Reynolds shear stresses -(uv)^^^- and -(uw)^^^-, such as the maximal and minimal in their cross-stream distribution at a local streamwise position, respectively. A hypothesis of spanwise wandering of the introduced streamwise vortex was presented, to understand the large quantitative discrepancy in the stress-strain relationship between the Reynolds stress -(uw)^^^- and the rate of strain S_yz. The non-isotropic and non-uniform distributions of Reynolds stresses play a dominant role on the decay of the streamwise vortex. In a comparison with some results obtained in turbulent boundary layers disturbed by streamwise vortices, structural differences between the wall jet and the boundary layer reveal in the non-isotropy of the Reynolds shear stresses, -(uv)^^^- and -(uw)^^^-.