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Sediment-laden gravity currents, or turbidity currents, are density-driven flows that transport vast quantities of particulate material across the floor of lakes and oceans. Turbidity currents are generated by slope failure or initiated when a sediment-laden flow enters into a lake or ocean; here, lofting or convective sedimentation processes may control flow dynamics. Depending upon the internal turbulent mixing, which keeps particles in suspension, turbidity currents can travel for thousands of kilometers across the seafloor. However, despite several competing theories, the process for the ultralong runout of these flows remains enigmatic. Turbidity currents often generate large sinuous channel–levee systems, and the dynamics of how turbidity currents flow around channel bends are strongly influenced by internal density and velocity structure, with large-scale flows being modified by the Coriolis force. Therefore, understanding some of the largest sedimentary structures on the Earth's surface depends on understanding the turbulence processes within turbidity currents.
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Supplemental Video 1: A video of a turbidity current flowing along a sinuous channel. Superelevation and overspill result in non-negligible fluid and buoyancy flux to the outer bank of submarine channel meander bends. Video provided by Dr Gareth M. Keevil, Sorby Environmental Fluid Dynamics, University of Leeds. Supplemental Video 2: Two videos taken from above of flow in a large sinuous channel. In first part of video there is no Coriolis force and the centrifugal force means that the gravity current alternates between the outside of channel bends. In the second part of video the background rotation is in the Southern Hemisphere sense, and the flow is strongly deflected to the left-hand side in both the left and right turning bends. Video provided by Dr Shahrazad Davarpanah Jazi, University of Toronto Scarborough (Davarpanah Jazi et al. 2020). Supplemental Video 3: Four videos showing the difference in dynamics between a standard turbidity current and a lofting turbidity current, and differences between an overflow with no sediment and a sediment laden overflow below which vigorous convective sediment occurs. The last video was provided by Dr Shahrazad Davarpanah Jazi, University of Toronto Scarborough (Davarpanah Jazi & Wells 2020).