Characterisation of the interaction between a boundary layer and a cavity using Digital Particle Velocimetry with Optical Flow

Abstract

An Optical Flow technique based on the use of Dynamic Programming has been applied to Particle Image Velocimetry yielding a significant increase in the accuracy and spatial resolution of the velocity field. Results are presented for an interaction between a laminar boundary layer and a cavity. The experimental characterisation of the interaction between a boundary layer and a cavity was developed in order to valid a three dimensional computation code based on the L.E.S. method (Large Eddies Simulation). The main application of this work is the study of the pollutant transport and dispersion in a canyon street. INTRODUCTION The aim of this investigation is to explore the possibility of using an optical flow technique in measuring fluid flow velocity. Classical flow visualisation is based on direct observation of tracer particles. Analysis of subsequent images searching for local displacements allows quantitative measurement of twodimensional flow fields. The optical flow method offer..