Shear-Layer Instabilities: Particle Image Velocimetry Measurements and Implications for Acoustics

The use of particle image velocimetry (PIV) to study the spatial and temporal features of unsteady fluid flow has increased dramatically in the past five to ten years. One particular application of PIV is to examine how shear-layer instabilities and turbulence lead to radiated sound. In this review, the basic operation of a PIV system is provided along with an introduction to the equations that relate unsteady fluid motion to sound. The references then illustrate how PIV is currently used in a number of canonical flow problems of interest in which the phenomena are dominated by shear-layer instabilities that lead to radiated noise. Specifically, cavity flows, flow over airfoils and cylinders, and finally jet flows are considered.