Particle image velocimetry

Particle image velocimetry (PIV) is the newest entrant to the field of fluid flow measurement and provides instantaneous velocity fields over global domains. As the name suggests, PIV records the position over time of small tracer particles introduced into the flow to extract the local fluid velocity. Thus, PIV represents a quantitative extension of the qualitative flow-visualization techniques that have been practised for several decades. The basic requirements for a PIV system are an optically transparent test-section, an illuminating light source (laser), a recording medium (film, CCD, or holographic plate), and a computer for image processing. This review article addresses the basics of the PIV technique such as PIV algorithms, optical considerations, tracer particles, illuminating lasers, recording hardware, errors in PIV measurements, and PIV vector processing.