| Density or gravity currents are flows driven by horizontal pressure gradients generated due to the action of gravity over fluids with different density. The density difference may be caused either by a scalar field that moves with the flow such as salinity or temperature, or by particles in suspension. The applications of such flows is very wide in many areas of engineering and geology. For example, density currents are flows well known to be one of the main sediment transport mechanisms into deep sea, whose deposits become oil reservoirs over geological time scales. Other examples of density currents are thunderstorm fronts, collapsing volcano ash plumes, contaminant releases in the environment, oil spills in the ocean, dust flows due to the collapse of buildings, flows originated by the discharge of a sediment-laden flow into oceans or lakes, and snow avalanches.; This work presents highly resolved simulations (on the order of ∼140 million grid points) of planar and cylindrical density currents for Reynolds numbers ranging from about 103 to about 104. A rigorous formulation of the problem that systematically incorporates the inertial, settling and coupling effects of the particles is also presented.; The simulations show in great detail the dynamics of the flow and the rich interaction between turbulent structures with a wide range of scales. Front spreading velocity, Kelvin-Helmholtz vortex dynamics, lobe and cleft formation and evolution, flow patterns, and bed shear stress patterns, are visualized and explored in detail. The simulation results are compared throughout the work to previously published experimental data and to laboratory experiments performed for this study and present very good agreement. |
