Fully Resolved Simulations of Dune Formation in Riverbeds

The formation and dynamics of dunes is an important phenomenon that occurs in many environmental systems, such as riverbeds. The physical interactions are complex and thus evaluating and quantifying the factors of influence is challenging. Simulation models can be used to conduct large scale parameter studies and allow a more detailed analysis of the system than laboratory experiments. Here, we present new coupled numerical models for sediment transport that are based on first principles. The lattice Boltzmann method is used in combination with a non-smooth granular dynamics model to simulate the fluid flow and the sediment particles. Numerical predictions of dune formation require a fully resolved modeling of the particulate flow which is only achieved by massively parallel simulations. For that purpose, the method employs advanced parallel grid refinement techniques and carefully designed compute kernels. The weak- and strong-scaling behavior is evaluated in detail and shows overall excellent parallel performance and efficiency.