Calculation of the fluid dynamic properties of coherent vortex wake patterns

The problem of characterizing the basic properties of turbulent shear flows continues to be one of both fundamental and practical interest. In the case of the turbulent wake of a bluff body the characterization of the underlying coherent structure of the vortex wake pattern is a particularly difficult problem. Conditional averaging of the measured velocity field in the wake of a D-section cylinder at a Reynolds number of 10,000 has elucidated the underlying coherent structure of the vortex wake. These measured velocities were matched with a vortex street model to estimate the circulation, spacing and core radii of the vortices. Similar computations were made with measured velocities from the wake of a flexible circular cylinder. These experiments were conducted at Reynolds numbers between 400 and 1300.