SUPERRESOLUTION PARTICLE IMAGING VELOCIMETRY

The spatial resolution of conventional high-image-density particle ima ge velocimetry (PIV) is determined by the size of the interrogation vo lume, which is typically a fraction of a millimetre. An improved metho d of PIV analysis is proposed in which the ultimate resolution of PIV is determined by the smaller of the mean spacing between particles and the displacement of the particles between light pulses. Since these d istances must be smaller than the interrogation spot size in the high- image-density limit, the new procedure is referred to as super-resolut ion. The method combines correlation analysis of the group of particle s in a spot with sub-interrogation-spot particle tracking. The theory of the procedure is described and evaluated using Monte Carlo simulati ons. The feasibility of enhancing resolution significantly is demonstr ated by re-analysing turbulent flow PIV data reported by Urushihara et al (1993). The in-plane resolution has been improved from 250 to 100 mu m.