Ultrafast two-dimensional ultrasonic speckle velocimetry: A tool in flow imaging

A technique for imaging fluid flows is proposed, based on the ultrafast analysis of the ultrasonic speckle signal backscattered by particles following the flow. Such an ultrasonic speckle velocimetry (USV) provides two-dimensional measurements of one component of the fluid velocity field at about 5000 frames per second. USV is applied to three different flows and future improvements of the technique are described. (C) 2001 American Institute of Physics.