3-DIMENSIONAL PARTICLE VELOCIMETRY

Light sheet particle image velocimetry (ply), which renders an instant aneous record of in-plane components of the flow velocity throughout t he sheet, is the starting point for the review of techniques to determ ine the three-dimensional velocity vector within an extended flow volu me. The analysis is restricted to particle velocimetry. The accuracy o f particle localization is given by the limits of high-resolution imag ing. More traditional variations of ply like coding of the depth posit ion in the sheet or scanning laser sheets are mentioned. Stereo PIV yi elds the out-of-plane velocity component and provides an understanding of basic relations for depth resolution. A novel back-projection sche me minimizes distortion effects and leads the way to a sophisticated p hase conjugate evaluation of holographic images. Particle holography i s introduced and the performance of various configurations like in-lin e, off-axis or multiple light sheet holography for flow applications i s discussed. The paper presents the state of the art in practical appl ications and provides material to assist in the selection of the metho d best suited for a given task.