Management of a Stronger Wall Jet by a Pair of Streamwise Vortices : Reynolds Stress Tensor and Production Terms

Abstract

Reynolds stress tensor for a complex three-dimensional flow field was investigated experimentally in a stronger wall jet managed by two typical kinds of streamwise vortex pair, namely, common -flow up and common-flow down cases. In the turbulent shear flow distorted by secondary flow and strong vorticity, six components of Reynolds stress tensor and rate of strain tensor were obtained with hot-wire measurement. The Reynolds shear stresses <uv> -and <uw> - are reasonably explained with occurrence of corresponding rate of strain-Sxy<=> ∼-(=U/=y)/2and -Sxz <=> ∼-(=U/=z)/2, respectively. The production terms and its global measure integrated in a cross-stream plane show that most of turbulent kinetic energy is produced by - <uv> - =U/=y as well known in many types of two -dimensional flow. In spite of influence by other velocity gradient components, the term -<v²> -=U/=y plays a dominant role on production of Reynolds shear stress component <uv> - through the whole shear layer. It is seen that mean velocity gradient =U/=y is still the most important distortion in such three-dimensional flow field.Difference in increasing rate of streamwise momentum flux between common -flow up and down cases can be related to difference in modification of the mean velocity gradient =U/=y.