Dual-Plane Correlation for Three-Dimensional Particle Image Velocimetry on Planar Domains

Abstract

Particle Image Velocimetry (PIV) is increasingly used to investigate unsteady flow velocity fields instantaneously. Thistechnique allows the recording of a complete velocity field in a plane of the flow within microseconds. In PIV the velocity vector field is usually determined by subdividing the recordings into small interrogation areas and employing particle tracking algorithms or statistical evaluation techniques. The method described in this paper is based onthe spatial cross-correlation of particle images stored on separate frames of each exposure. It is expanded by the analysis of the correlation peak heights. The correlation value depends on the portion of paired particle images, which itself depends on the out-of-plane velocity component, but also on other parameters such as background light, varying image size and number, loss of pairs dueto in-plane motion. To avoid problems arising from these other influences, images from a displaced light sheet plane,