HYDRODYNAMIC BEHAVIOR OF FLOW PAST THREE TYPICALLY ARRANGED CIRCULAR PIERS ON DIFFERENT HORIZONTAL PLANES

Abstract

In this paper an attempt has been made to study the hydrodynamic behavior of flow in terms of three-dimensional turbulent flow patterns and characteristics around three identical circular shaped piers of 7 cm diameter at two horizontal planes. Three pier groups were placed with inline and eccentric arrangement in a staggered manner on a flume. The experiment was conducted under clear water scour conditions. In this experiment two inline piers were placed along the flow, and a third pier was placed eccentrically in the middle of the two inline piers with a transverse spacing. The hydrodynamic effects of the three-pier arrangement were investigated near the bed and near the middle of the flow depth, in order to show the flow behavior at the area close and far away from the sediment bed, respectively. All over the scoured zone at two horizontal planes, the contour profiles and distributions of the time-averaged longitudinal, transverse, and vertical velocity components, turbulence kinetic energy, and turbulence intensities are determined and analyzed. Velocity vectors and absolute velocity obtained from velocity fields are used to show further hydrodynamic flow features. The scour depth of the eccentric circular pier was observed to be higher than the inline front and inline rear circular piers. The three-pier arrangement and the interference between the circular piers play an important role in the flow characteristics and in the creation and formation of the greatest scour depth at the eccentric middle pier.