Measurement and Characteristic Analysis of Turbulent Flow near Permeable Spur Dike

Abstract

To disclose the turbulence features near a permeable spur dike, this paper measures the three-dimensional (3D) instantaneous velocity at different vertical lines and depths around the permeable spur dike through acoustic Doppler velocimetry (ADV). The relative turbulence intensity and Reynolds stress were calculated for each measuring point, and the distribution features of different turbulence structures were analyzed along the water depth. Experimental results show that: within the length of the dike, the turbulence intensity and Reynolds stress in the downstream of the dike are much greater than those in the upstream. In the downstream of the dike, the turbulence intensity in the root and body regions peaks in the dike crest layer, but that at other positions minimizes in that layer (but peaks on the water surface or river bottom). In the upstream, ejection and sweeping are the dominant turbulence structures; the two structures also dominate near the free layer at the bottom in the downstream; outward and inward interactions dominate near the dike crest layer in the downstream.