Numerical modeling of local scour at a submerged weir with a downstream slope using a coupled moving-mesh and masked-element approach

This paper presents a model for local scour at submerged weirs with downstream slopes that uses a coupled moving-mesh and masked-element approach. In the developed model, the fluid-sediment interface is tracked using a moving-mesh technique, and the effects of the structure on the hydrodynamics and bed morphology are resolved using a masked-element technique. Compared to traditional sediment scour models, based on the moving-mesh technique, the present model has the advantage of allowing for a simpler setup of the computational grids and a larger-amplitude deformation. Laboratory experiments on local scour at a submerged weir with a downstream slope were conducted, which provided bed profiles at different time instants. The results obtained by the present model are compared to the experimental data. The comparisons demonstrate the performance of the model in satisfactorily predicting local scour at a submerged weir with a downstream slope. The model was further modified and employed to carry out additional computations to investigate the influence of various parameters and sub-models. •A new laboratory experiment for local scour at a submerged weir with a downstream slope is conducted.•The flow and scour are simulated using a coupled moving-mesh and masked-element approach.•The effects of various parameters are investigated.•The performances of different model are evaluated.