Slope control on ambient fluid entrainment of subaqueous density flows with steady sustained inflows

Abstract

Entrainment of density flows is a key parameter in constructing predictive models of global climate, ocean flows, and turbidity currents. Our numerical experiment, which included 10 subaqueous dilute density flows with a steady sustained inflow (SSI) on a 2D channel bed slope varying from 0.1° to 90°, showed that in the slope range of 0.1–20°, there is a linear relationship between the ambient fluid entrainment and channel bed slope. We also found a power law relation between the bulk Richardson number and bed slope. On a larger slope bed, these relations broke down due to the strong head drag, which suggests that there exists a regime change from bed-supported to plunging flows at around 20° for SSI density flows on a slope bed. These findings may provide a way to quickly evaluate or parameterize subaqueous SSI density flows in the suggested slope range.