3D Numerical Study on Local Scour Around Spur Dikes with Different Layout Angles

A 3D numerical model is developed to investigate the flow motion and sediment transport around grouped spur dikes with different layout angles. This model solves Navier-Stokes equations for fluid motion, by adopting the Volume of Fluid (VOF) method to track the free surface motion and Large Eddy Simulation (LES) to capture turbulent transport and dissipation. The spur dike and sand bed are treated by the porous media method (PMM) with different porosity and particle size. The suspended load and bedload are treated separately but combined together to update bed evolution. Carefully selected flume experiments are introduced to verify the model. The simulations of the downward-angled spur dikes case and the normal-angled spur dikes case are then conducted. The detailed analyses on the temporal and spatial variation of flow intensity, vortex patterns, sediment concentration and shapes of scour holes are made for these two cases. Finally, the scour responses to different groin angles are summarized.