VelocityVorticity Decomposition of the Reynolds Stress Gradient in a Shear Layer
Scott C. Morris Department of Aerospace and Mechanical Engineering University of Notre Dame 110 Hessert Laboratory, Notre Dame, IN 46556 USA
John F. Foss Department of Mechanical Engineering Michigan State University East Lansing, Ml 48824 USA
Aren M. Hellum Department of Mechanical Engineering Michigan State University East Lansing, Ml 48824 USA
ResumoTime series measurments of velocity and vorticity using a four sensor hotwire technique have been acquired in a large scale single stream shear layer. The Reynolds stress gradient which appears in the time averaged momentum equation can be written in terms of the velocityvorticity products. The experimental data allows for the evaluation of these quantities, and the spectral content of the time series provides insight into the scales of motion which lead to the time averaged values.
The power spectral density function for the vorticity time series (ω_{z}, ω_{y}) show substantial values at a wide range of wave numbers. The velocityvorticity products also indicates a wide distribution in wave number space. This indicates the existence of anisotropic motions which contribute to the Reynolds shear stress gradient at wave numbers at both very high and very low wave numbers.
