Scour around Bridge Piers: Numerical Investigations of the Longitudinal Biconcave Pier Shape

Abstract

The flow pattern around a bridge pier and the scouring phenomenon are very complicated. The basic mechanism causing local scour is the down-flow at the upstream face of the pier. It is understood that the horseshoe vortex is the key mechanism that leads to the local scour around pier; existing literature revealed that the strength of the down-flow, horseshoe vortex and the wake vortex are greater in the case of square piers compared to circular piers. In this paper we have investigated a new longitudinal biconcave bridge pier shape that reduces better the bed shear stress. For that purpose, a number of numerical simulations have been carried out using a Finite Volume Method (FVM) and for the turbulence model we have chosen the Detached Eddy Simulation (DES) for its capability to capture the rich dynamics of the horseshoe vortex at the upstream junction between the pier and the bed.The present study shows that the new longitudinal biconcave bridge pier shape reduces 10 % to 12 % the bed shear stress at the junction between the pier and the bed in other hand this shape increases the bed shear stress about 20 % but at a distance of D downstream the bridge pier in the flow direction.

Computational Aeroacoustic Investigation of Airfoil Cascades

“…Periodic Vortex Shedding (VS) in flow past solid bodies has a great importance in case of turbomachinery and other areas of fluid mechanics [1][2][3] as well. In case of axial flow fans, a significant part of the noise emitted is aerodynamically generated, and originates from noise sources associated to the fan blades [4], and one of the strongest of these noise sources is the periodic VS from the fan blade surface.…”