Investigation of Vorticity Effects on Local Scouring

摘要

This paper describes a numerical model developed to simulate flow and bed deformation around hydraulic structures. The model uses an improved formula for the bed shear stress by applying vorticity effect and solves the full three-dimensional Reynolds-averaged Navier-Stokes equations to calculate the flow field. The capability for numerical models to predict local scour is severely restricted by the sediment transport formula. Up to now, the scour computations were developed based on general sedimentation formula through a straight unobstructed flow path. The new sedimentation formula introduced in this paper can take into account vortices that affect the local scour process. To verify the model, a bridge pier and a groyne, which are considered as typical river-engineering structures, were simulated in different hydraulic conditions by applying both the ordinary bed shear stress equation and the new one. Comparisons show that the new equation could predict the scour more accurately than the ordinary one.