On the transition of PIV into the digital age: Recounting 20 years of digital PIV

Abstract

Early 1989 the first image sequences of single exposed particle images were acquired for a low speed water flow and for the first time demonstrated the double-frame, single-exposure PIV recording and processing concept, that was to become the most common implementation of PIV up until today. The presentation provides a historical perspective of the development of digital PIV in the presence of the then already well established photographic PIV methods. Initially the implementation of the two techniques seemed to be almost contradictory, but a steady improvement of the theoretical background during the 1990's clarified that the two techniques are merely different implementations of the same measurement principle. Digital processing of photographic PIV recordings became possible with the emergence of slide scanners which ultimately replaced the optical interrogation methods. Soon thereafter new camera technology based on interline-transfer CCD sensors allowed the capture of two separate images on the microsecond scale and for the first time provided reliable digital PIV measurements of high speed flows in aerodynamics. A continual growth in sensor resolution nowadays provides a spatial resolution that rivals that of high-resolution 35 mm photographic film.