Smooth shear layers with a disturbed turbulence structure

After a brief phenomenological description of the causes and effects of the disturbance to the turbulence structure, the concept of relaxation is defined. Attempts made hitherto to describe this shear layer mathematically are reviewed. Experimental work on the shear layer with a disturbed turbulence structure is reported on. The experiments shed light on some essential physical characteristics in this flow, such as the appearance of different relaxation lengths for the various flow quantities pressure, mean velocity, and Reynolds stresses. An attempt is made to explain this feature through a theoretical framework. In the ensuing discussion the state of the art of computation of these shear layers is assessed and directions for further work are pointed out.