Entrainment In Gravity Currents Research Articles

Slope dependence of self-similar structure and entrainment in gravity currents

Results from seven direct and large-eddy simulations of gravity currents on slopes ranging from 0.14 $^{\circ }$ to 2.86 $^{\circ }$ that span from the subcritical to the supercritical regime are studied. By considering a long domain, attention is focused on the near-self-similar state approached by these currents far downstream. In the self-similar limit, the various shape factors, local Richardson number, entrainment coefficient, velocity scale and basal drag coefficient reach a constant value, while the current height, volume and momentum fluxes continue to increase linearly. Their dependence on slope is presented.

Entrainment in bottom gravity currents over complex topography from three‐dimensional nonhydrostatic simulations

By recognizing that oceanic overflows follow the seafloor morphology, which shows a self‐similar structure at spatial scales ranging from 100 km to 1 m, the impact of topographic bumps on entrainment in gravity currents is investigated using a 3D nonhydrostatic spectral element model. It is found that a bumpy surface can lead to a significant enhancement of entrainment compared to a smooth surface. The change in entrainment is parameterized as a function of statistical estimates of the amplitude and wavenumber parameters of bumps with respect to the background slope.