Quasi-stationary flow structure in turbidity currents
| Autor: | Yasushi Takeda, Hide Sakaguchi, Mikito Furuichi, Shun Nomura, Giovanni De Cesare |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
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Turbidity current density currents Stratigraphy Flow (psychology) 0207 environmental engineering Fluvial mass valance 02 engineering and technology 010501 environmental sciences gravity currents 01 natural sciences spatiotemporal evolution velocity field 020701 environmental engineering turbidity current 0105 earth and related environmental sciences turbulence structure Turbulence Sediment speed Geology Mechanics image processing ultrasound doppler velocity profiling Flume velocity structure simulations Current (fluid) flume experiment Sediment transport |
| Zdroj: | International Journal of Sediment Research. 35:659-665 |
| ISSN: | 1001-6279 |
| DOI: | 10.1016/j.ijsrc.2020.04.003 |
| Popis: | A turbidity current is a particle-laden current driven by density differences due to suspended sediment particles. Turbidity currents can transport large amounts of sediment down slopes over great distances, and play a significant role in fluvial, lake and submarine systems. To better understand the sediment transport process, the flow system of an experimentally produced turbidity current in an inclined flume was investigated using video processing. We observed that the current progresses with constant frontal velocity and maintains an unchanged global interface geometry. In addition, the spatio-temporal profiles of the inner mean and turbulence velocity obtained by ultrasound velocity profiler (UVP) showed that similar distributions were maintained, with low dissipation. The results indicate that the turbidity current progressed in a quasi-stationary state, which enabled long-distance sediment transport. To understand the mechanisms behind the quasi-stationary flow, we analyzed the forces acting on the turbidity current. We found that under particular densities of suspended particles, the gravitational force is balanced by the viscous forces along the slope direction. We conclude that this specific force balance induces the quasi-stationary flow structure, enabling the long-distance transport of a substantial amount of sediment downstream with low dissipation. (C) 2020 International Research and Training Centre on Erosion and Sedimentation/the World Association for Sedimentation and Erosion Research. Published by Elsevier B.V. All rights reserved. |
| Databáze: | OpenAIRE |
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