Effect of Schmidt Number on Dynamics of Particle-Driven Gravity Currents

Direct numerical simulations (DNS) of particulate gravity currents in a lock-exchange set-up are presented. The effect of the Schmidt number Sc on the current dynamics is analyzed by means of Eulerian-Eulerian simulations. Eulerian-Lagrangian simulations are used as a benchmark for assessing the results of Eulerian-Eulerian simulations. The Schmidt number Sc, the particle properties and the Reynolds number Re are varied. A significant influence of Sc was found, whose magnitude depends on the particle properties (being highest for fine particles) and on Re. For the finest particles used, the deposited particle mass was found to be different by almost 25% when comparing Lagrangian and Eulerian simulations with Sc = 1. The instantaneous flow features like the vorticity field are affected as well. When doubling Re, the effect was still found to be significant for finer particles, though less than that for low Re.