Prediction of the Local Scour at the Bridge Square Pier Using a 3D Numerical Model

Nguyen Viet Thanh,Tran Dinh Nghien,Dang Huu Chung

doi:10.4236/ojapps.2014.42005

Nguyen Viet Thanh, Tran Dinh Nghien + Show 1 more

Open Access

https://doi.org/10.4236/ojapps.2014.42005

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Abstract

In this paper, the problem on local scour around a single square pier was studied by using both the numerical and physical models. The numerical model for the study is FSUM based on a finite-difference method to solve the Reynolds averaged Navier-Stokes equations (RANS) and the equations for suspended sediment concentration and bed morphology. The computed result was verified through data measured in the experimental flume with a sand bed. In general, the typical features of local scour around the pier were successfully simulated by FSUM, such as stream flow, bow flow, down flow, horseshoe vortex. The comparison between the computation and experiment data shows a quite good fitness. Both numerical model and experiment results show that the maximum scour depth occurs at two front edges of the pier. Although the computed result shows a little bigger scour depth in comparison with the measurement in the physical model, it still confirms the reliability of numerical model in some measure.

Highlights

Local scour of alluvial channel beds around obstructions is a problem of continuing interest
It can be inferred that the down flow may exert forces on the bed that initiate the eddy that causes the increase of local scour around the pier
The time duration of about 4 hours for such an experiment is enough to investigate in more details the process of erosion around a pier

Summary

Introduction

Local scour of alluvial channel beds around obstructions is a problem of continuing interest. Olsen et al (1993) [5] predicted local scour developing processes using a three-dimensional flow and sediment transport model They solved the Reynolds equations with the k-ε model for turbulence closure. Wang et al (1999) [10] examined the importance of including various flow effects on sediment transport They used a numerical model to simulate the three dimensional flow conditions around a pile and in a scour hole. Wang et al (1999) [10] simulated an evolution of the scour hole developing around the bridge pier by using CCHE3D They examined the importance of including various flow effects on sediment transport. Some treatments on local bed roughness are incorporated into FSUM model to improve the result of numerical simulation

Experimental Work and Result

FSUM Model and Setup Procedure

Numerical Results and Comparison

Conclusions