Flow Evolution in Submarine Channel Bends: Experimental Insights Into Flow Tuning

Gareth M. Keevil, William D. McCaffrey, and Jeff Peakall
School of Earth and Environment, University of Leeds, Leeds, United Kingdom

Submarine channels are the primary conduit for the transport of clastic sediment into the deep oceans and as such have a vital role in the distribution of sediment. To fully understand the mechanisms of sediment distribution it is necessary to investigate the fluid dynamics that operate within submarine channels, as it is the fluid flow which governs sediment deposition and redistribution. Several recent laboratory and numerical studies have focused on the structure of fluid velocity and sediment concentration with single bends. This paper focuses on fluid flow within compound channel bends.

A series of experiments is presented in which saline gravity currents flowed through a fixed form channel model which comprised 10 bend pairs. The data reveal significant channel overspill and the presence of secondary flow cells best developed at bend apexes. The flow discharge was shown to decrease downstream with distance until equilibrium was reached at which point the discharge remained constant.

This work demonstrates that compound bends significantly adjust or tune the flow within submarine channels. This tuning acts to equilibrate the magnitude of the flow with the geometric capacity of the channel. As a consequence of the flow tuning channel overspill was shown to be most significant within the first few bends. A greater understanding of flow within compound channel bends will lead to a better understanding of bend evolution, channel migration, stability and also bed thickness distribution patterns within levees and terminal lobes.

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas