Abstract
Local scour around structures is a natural process that impacts the design of submerged hydraulic structures. The phenomenon of erosion and movement of sediment particles in the vicinity of a submerged object is a result of the interaction between the turbulent flow and a bed of sediment particles. In this work Computational Fluid Dynamics (CFD) coupled to Discrete Element Method (DEM) is used to numerically predict the temporal evolution and morphology of the scour around a submerged structure. Simulations of scour and morphology are typically performed using Eulerian-Eulerian representations and thus avoid the excessive computational resources required to track all the discrete sediment particles of the bed material in the domain of interest. In the current work a periodic domain is assumed making this type of simulation more feasible for CFD-DEM simulations. An augmented soft sphere collision, which includes rolling friction and adhesive forces is used for representing the contact physics. The simulation was run for more than 50 s of real time. The temporal evolution of the scour around the submerged obstacle is investigated and compared to published experimental results and past simulations. The current work shows a deeper initial scour compared to experiment. The build-up of the ridges downstream start at the same rate predicted by experiment but seem to progress at a slower rate after 15s.
