1994 Volume 38 Pages 697-702
Many turbulence measurements have been ever conducted by point measurement techniques such as hot-film anemometers (CTA) and laser Doppler anemometers (LDA). Compared with these techniques, coherent vortex phenomena are easily recognized by flow visualization techniques.
In this study, images of very small 100μm diameter particles uniformly scattered in compound open-channel flows were taken using a CCD camera and 2W Argon-ion laser slit illumination. These images were stored through frame memory board from an optic disc controlled by a personal computer. Instantaneous velocities at many points in the laser slit plane were measured from these continuous four images of one particle. This new method is called the “Particle -Image Velocimetry (PIV)”, and seems to be very powerful to investigate coherent vortices in space and time because simultaneous velocities at every point can be obtained.
