Particle Image Velocimetry (PIV) uses the displacement of small particles in the flow between successive light sheet exposures for velocity measurements. This method is a whole field technique, i.e. every recording captures the whole light sheet area at once.
This picture below shows the PIV-recording and the evaluation of incoming particles in a Mach 2 flow, hitting a wedge surface. Since PIV allows the separation of incoming and reflected particle velocities in the auto-correlation domain, two velocity fields were obtained, thus providing the energy left in the surface by the particles. This investigation gave information on the erosion behavior of different sized particles in transonic and supersonic flows.