An interferometric study of organized structures in wakes of circular cylinders

Double-pulse diffuse-illumination interferometry has been used to study the organized structures in the wake of a circular cylinder (M = 0.6, Re(d) = 300,000). The interferograms show striking similarities to the flow visualization pictures of the incompressible wakes of circular cylinders as obtained by other investigators. In particular, the interferograms taken with very short pulse intervals show concentrations of fine scale turbulence in the von Karman vortices and the existence of streamwise vortices between these counter-rotating largescale vortices. The fact that most of the features observed in low speed wakes using a variety of techniques can be observed in the interferograms illustrates the potential of interferometry for the study of turbulent structures in compressible flows. (Author)