The Role of The Coriolis Force on Deep Marine Gravity Currents in Sinuous Channels

Nilufan, Xiaokaiti

Abstract

Gravity currents can be generated by density differences created by high suspended sediment concentrations in the form of turbidity currents, which can also transport significant volumes of near surface waters into the deep ocean. These flows are often concentrated in downslope channels that link and act as conduits from the continental shelves to the deep sea. Thus, understanding these mixing and exchange processes are critical to furthering our understanding of key ecosystems, the global carbon cycle and climate.
Many parameters affect density-driven flow dynamics, including density difference, bed roughness, and bottom slope. At large-scales, in real-world environments, the rotational motion of the earth generates pseudo-forces, i.e., Coriolis force that increase with latitude. In extreme limits this may become as important as the inertial force of average fluid motion. As such, this force also affects flow dynamics.
The formation and development of submarine channels are influenced by dynamic interaction of turbidity currents with the seafloor and the force acting on the flow. Laboratory experiments were conducted using world’s largest rotating platform to investigate how the Earth’s rotation might influence the internal flow structure and secondary flow at a bend apex. The downstream and cross stream velocity, as well as the density data for various rotating rates, across a range of Rossby numbers were gathered and analysed in order to investigate how buoyancy & velocity of channelized turbidity currents effect ambient fluid entrainment under different Rossby numbers (RO).
It is suggested that enhanced secondary flow with increasing Coriolis force results in reduced mixing. Coriolis force is responsible for changes in the direction of the bottom boundary layer of a gravity current and the location of the maximum velocity core, leading to result in uneven right and left-turning bends. The denser fluid, on the other hand, always remains close to the outer bend, creating a hydraulic mechanism for stabilizing bend evolution at higher latitudes. Strong Coriolis forces, in addition, can change the course of near-bed secondary flow.

Citation

Nilufan, X. (2023). The Role of The Coriolis Force on Deep Marine Gravity Currents in Sinuous Channels. (Thesis). University of Hull. https://hull-repository.worktribe.com/output/4564869

• Thesis Type: Thesis
• Deposit Date: Feb 27, 2024
• Publicly Available Date: Mar 7, 2024
• Keywords: Geography
• Public URL: https://hull-repository.worktribe.com/output/4564869
• Additional Information: Energy & Environment Institute; University of Hull
• Award Date: Jan 24, 2024