DIRECT NUMERICAL SIMULATIONS OF PARTICLE-DRIVEN GRAVITY CURRENTS IN A BASIN CONFIGURATION

etc15 Tracking Number 94

Three-dimensional highly resolved Direct Numerical Simulations (DNS) of a particle-driven gravity current are presented for the lock-exchange problem in a basin configuration. Two Reynolds numbers are investigated in order to identify differences in the flow structures and dynamics. For this numerical study, we limit our investigations to gravity currents over a flat bed in which density differences are small enough for the Boussinesq approximation to be valid. The concentration of particles is described in an Eulerian fashion by using a transport equation combined with the incompressible Navier-Stokes equations, with possibility of particles deposition but no erosion and re-suspension. For this original flow configuration, it is found that the Reynolds number has a strong influence on the flow, in particular on the deposition pattern over the flat bed. Furthermore, we found out that the well-known lobe-and-cleft patterns at the head of the current have a different shape than what is usually observed for the lock-exchange problem in a channel configuration. The curvated shape of the front has a significant twisting effect on the structures at the head of the current.