Turbulence Measurements in Model Settling Tank

Abstract

Turbulence measurements are made in the inlet region of a rectangular laboratory settling tank with a two‐component laser‐Doppler system. The flow fields from a plane jet impinging on two types of deflector, at constant depth and discharge, are studied. Effects due to density differences or the presence of sediment are not considered. Although the two flow fields exhibit marked difference in terms of the extent of their recirculation regions and the extent of regions of high turbulent transport, flow‐through curves from tracer tests indicate little difference. A comparison to the case without deflector shows improved hydraulic efficiency, attributable to the inhibition of short‐circuiting effects or to increased initial mixing. Strong and complex three‐dimensional effects are found. Implications for design as well as numerical modeling are discussed.