Keevil, Gareth1, Jeff Peakall1, Jim Best1
(1) University of Leeds, Leeds, United Kingdom
ABSTRACT: Channelised Turbidity Currents: New Experimental Insights Into Flow Structure and Secondary Flow
Submarine channels have long been considered analogous to meandering fluvial channels due to their similar planform geometry, these analogies being based largely on morphological characteristics, not observed fluid processes. Very little is known about the fluid dynamics of submarine channels at various stages of flow or channel evolution, limiting our ability to interpret the nature of these channels.
This paper will present results from a series of new experiments where saline gravity currents were run through a submerged, fixed form, sinuous channel model. Ultrasonic velocity profiling provided high-resolution two-dimensional flow fields in multiple orientations, allowing for the first time visualisation and quantification of velocity profiles and secondary flows of a turbidity current within a sinuous submarine channel. The data reveals secondary flow cells are best developed at bend apexes and the basal component of the flow cell moves from the inside to outside of the bend, the reverse of that expected in classic fluvial models. The same experimental facility and channel model has been used to quantify and visualise a fluvial channel, providing a unique comparison between a submarine and fluvial channel.
These results are of prime importance when assessing the validity of comparisons between submarine and fluvial channels, and the role of secondary flow cells in the migration and evolution of meander bends. This work demonstrates the fundamental nature of secondary flow in submarine channels, and subsequent controls on levee overspill, suggesting the flow processes controlling the evolution and migration of submarine and fluvial channels must fundamentally differ.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.