Influence of Scour Development on Turbulent Flow Field in Front of a Bridge Pier

Jinzhao Li,Zhiwen Yang,Yilin Yang

doi:10.3390/w12092370

Abstract

This study concerns the turbulent flow field influenced by the scour development around a bridge pier. The scour hole evolution as well as the temporal variation of scour depth around the pier were firstly analyzed. Subsequently, the flow fields in front of the pier at different instants during the scour process were measured using particle image velocimetry (PIV). It shows that the scour depth at the pier front exceeds that of the pier side at the later scouring stage. The temporal development of scour depth can be well predicted by a simple practical engineering model based on an exponential function with a change in the two adjustable coefficients. The flow field indicates that with the development of scour hole, the downward flow in front of the pier becomes more prominent, meanwhile the flow becomes more turbulent. The variation tendency for both velocities and turbulence intensities along the streamwise direction in front the pier shows similarity. The Reynolds shear stress generally increases with developing scour hole, and the region with large value enlarges and moves upstream of the scour hole.

Highlights

Local scour around bridge piers is resulted from the interaction of local flow field with riverbed sediment, which is one of concerned issues in hydraulic engineering [1]
The Flow straightener was set at the entrance of the flume to calm the turbulence of flow, and a tailgate was set at the outlet of set at the entrance of the flume to calm the turbulence of flow, and a tailgate was set at the outlet of the flume to adjust the water depth
We mainly on we mainly focus on the region in front of the pier where the maximum scour depth is normally occurred and theof influence of turbulent horseshoe vortex is most pronounced

Summary

Introduction

Local scour around bridge piers is resulted from the interaction of local flow field with riverbed sediment, which is one of concerned issues in hydraulic engineering [1]. It is essential to accurately estimate the scour depth around piers to guarantee the safety of bridges. In the past several decades, numerous studies on pier scour have been conducted focusing on the equilibrium scour depth, that is the maximum scour depth when it reaches to the equilibrium state [3,4]. In reality, natural flood duration is usually far shorter than what is needed to reach the equilibrium scour depth [5]. In order to predict the scour depth reasonably and accurately from the viewpoints of both the safe and economical design of bridge pier, it is necessary to study and identify the variation of scour depth with time during the pier scouring process

Objectives

Methods

Conclusion