Turbulent river flow can cause severe riverbed erosion around bridge piers and eventually lead to bridge failures. Because of its engineering relevance, the study of river flow around bridge piers has attracted considerable research attentions in the recent decades. Some experimental results of good quality have been reported in the literature. However, the complex interaction of the free surface flow, bridge piers and riverbed sediments is still poorly understood. The objective of this study is to numerically investigate the structure of free surface flow with high resolutions. The scenario of a fixed riverbed without sediment transport is considered. For given conditions of discharge, bridge pier configuration and equilibrium scour hole, the flow field is computed with a three-dimensional hydrodynamics model. The present simulations allow for varying grid resolutions to achieve high computational efficiency. The model results are compared with available flow measurements from laboratory experiments. The results are useful for an extension of three-dimensional modelling to include bedload transport of sediments of different sizes, bed level change, continuous feedback to the flow field and local slope instability.
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