Tracking and Pair Dispersion Analysis of Buoyant Particles in a Turbulent Shear Flow

Abstract

Presented are experimental measurements of one and two-particle dispersion in a turbulent shear flow. The baseline flow is a well-characterized high Reynolds number turbulent submerged round jet. Buoyant air bubbles and canola oil droplets were injected into the jet within the self-similar region at five injection locations and five jet Reynolds numbers ranging from 18,000 to 34,000. Images of two particles, injected simultaneously, were obtained from high-speed shadowgraphy. The particles were then tracked using a four-frame predictive algorithm. The influence of mean shear and turbulent fluctuations on dispersion is analyzed for initial positions where a mean velocity shear is superimposed on turbulent fluctuations. The results were analyzed to determine the influence of the density ratio, the non-dimensional shear rate, Reynolds number, and the turbulence intensity (these last three associated with the location of injection) on single-particle and two-particle dispersion.