Experimental study of flow and turbulence characteristics around simple and complex piers using PIV

This study investigates the flow around Complex Pier (CP) with elliptical pile-cap and compares the results with that of Simple Pier (SP). The velocity data were recorded using Particle Image Velocimetry (PIV) along upstream and downstream of piers for three Reynolds numbers (Re). The study addresses the mean flows, Reynolds stresses, velocity vectors, vorticity, turbulent kinetic energy and power spectra around piers. The results showed that the flow field around the CP was significantly different from that of SP. A reverse flow was dominant on the downstream of SP for lower Re, but with an increase in Re, the reverse flow shifted towards upstream, whereas, in the downstream of CP, it was only confined to the column region. Vorticity contours showed dominant clockwise layers on the upstream of both piers, while at the downstream, anti-clockwise layers were observed in the entire flow depth for SP but it was only restricted to the column region for CP. The spectral analysis of velocity data was also performed for both the piers to examine the vortex shedding frequency.