Numerical modeling of flow and bed evolution in meandering submarine channels

We present a numerical model of flow and bed morphology in meandering submarine channels. The conservation equations of fluid mass and momentum, suspended sediment concentration, and turbulent kinetic energy are expressed in depth-averaged form and an intrinsic coordinate system. These equations, along with the Exner equation of bed sediment continuity, are solved using a predictor-corrector explicit finite difference scheme. The numerical model is validated against laboratory experiments conducted in a straight flume. The model is generalized to any sinuous planform geometry, but this study focuses on sine-generated sinuous channels. A series of numerical experiments have been performed with various inflow conditions and channel shapes to characterize the nature of in-channel flow, deposition, and erosion, as well to investigate the tendency for meander migration. The model predicts an overall decrease in depth-averaged current velocity and suspended sediment concentration in the down-channel direction. Variations of current thickness, streamwise velocity, concentration, and bed level across the channel have been found to increase with an increase in channel curvature. Model runs made with erosional currents display significant change in bed level in the lateral direction because of erosion near the out side and deposition near the inside of a bend. The lateral bed slope generated by the flow of a depositional current is found to be relatively small. Model results are compared with the sedimentation pattern of a seismically interpreted buried submarine channel.