Fundamental Issues and Latest Development in Holographic Particle Image Velocimetry

Abstract

Holographic PIV (HPIV) is currently the most promising technique for truly instantaneous, three-dimensional (3D), three-component (3C) velocity field measurements for complex flows including turbulent and multiphase flows. This paper reports new understanding on some fundamental issues and challenges in HPIV including the complex 3D imaging characteristics, the extraction of full particle information (intensities, sizes, and locations) in 3D space, the extraction of particle displacements, and the huge data volume to process. The latest off-axis HPIV system will be presented, which incorporates the new understanding of imaging characteristics of particle holography, careful development of data processing algorithms, and a well-designed distributed parallel processing system. We will demonstrate capabilities of HPIV by a semi-time-series measurement of instantaneous 3D, 3C velocity fields in highly 3D vortical flow.