Jasim Imran¹, Ahmed Kassem¹

(1) University of South Carolina, Columbia, SC

ABSTRACT: Flow Structure and Bed Topography in Submarine Meandering Channels

A three-dimensional numerical model is used to investigate the secondary currents, flow stripping, and the bed topography in submarine meandering channels. The model solves the Reynolds-averaging Navier-Stokes equations along with the sediment conservation equation and the temporal bed deformation equation. Turbulence closure is obtained with the standard k-e model modified for the buoyancy effect. The fully three-dimensional model is applied to obtain the vertical structure of flow and concentration of a turbidity current in both streamwise, and lateral directions. Two distinct circulation zones have been noticed in the bend. The first one circulates in the clockwise direction from outside of the bend to the inside along the bed as typical secondary currents do in subaerial channels. The second circulation zone is anticlockwise from the ambient water to the super-elevated interface. The later is due to the displacement of the ambient water by turbidity current accelerating towards the outside of the bend. Vertical integration of the computed lateral velocity provides the detail structure of the secondary current which is compared with that in the subaerial environment. The investigation of sediment concentration field shows a significantly high super elevation of the interface between the dense and lighter fluid above. This is in agreement with acoustic image of a turbidity current passing through a bend in a fjord channel. Also, flow stripping over the outside of the bend is noticed. In addition, important physical processes such as erosion and sedimentation in the channel and on the backside of the levee are also investigated.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado