Abstract
A wind tunnel experiment has been made on the structure of turbulence in a thermally stratified shear layer. Effects of buoyancy on the mean flow and turbulence were studied. Both stable and unstable stratified layers were realized. In the stable stratified flow the highest Richardson number is around unity.
The velocity gradient either increases or decreases depending on whether the flow is unstable or stable. Correspondingly, the turbulence intensity is reduced with increasing stability, whereas under unstable conditions it is enhanced. The measured thermal flux shows a remarkable difference in stable and unstable layer.
With an appropriate normalization the spectra and cospectra changes according to the Richardson number at low frequencies, however they collapse into a single universal curve at high frequencies. This agrees very well with results of field observations.
