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.

Keywords:

• Ambient fluid entrainment
• bulk Richardson number
• slope
• subaqueous density flows
• steady sustained inflow

Acknowledgments

Funds from the National Natural Science Foundation of China are gratefully acknowledged. We are grateful to Dr H.M. Pantin for his constructive suggestions and editing of an earlier version of this manuscript.

We thank LetPub (www.letpub.com) for its linguistic assistance during the preparation of this manuscript.

Funding

This work was supported by the National Natural Science Foundation of China [grant numbers: 40972086, 41172103, and 41376071].