3-D flow investigations by rainbow volumic velocimetry (RVV) : recent progress

This paper presents the last development of an original method intended for experimental investigations of 3D flows: the Rainbow Volumic Velocimetry (RVV). In this technique, the flow is seeded with tracers whose positions are recorded by a 3CCD camera connected to a frame grabber. Insted of being lightened in a plan (classical tomography), the flow is lightened in a volume with a continuous spectrum illumination in order to introduce additional information in images. Thereby multicolored images are recorded. The first two spatial coordinates of a tracer are obtained like in classical PTV and the third coordinate is determined thanks to a wavelength coding, the tracer color being directly connected to its depth position.