HR: 0800h
AN: H41B-0497    [Abstracts]
TI: Sandbar Formation Under Surface Waves
AU: * Hancock, M J
EM: hancock@mit.edu
AF: Matthew J. Hancock, Dept. of Mathematics, MIT Bldg 2, Room 339, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
AU: Landry, B J
EM: blandry@alum.mit.edu
AF: Blake J. Landry, Dept. of Civil & Environmental Engineering, University of Illinois, Urbana-Champaign, IL 61801, United States
AU: Mei, C C
EM: ccmei@mit.edu
AF: Chiang C. Mei, Dept. of Civil & Environmental Engineering, MIT Bldg 1, Room 346, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
AB: We report a combined theoretical and experimental study of sandbar formation under simple-harmonic surface waves. For coarse grains and weak waves, an established empirical rule of bedload transport is used with an asymptotic theory for the fluid flow. The surface waves are governed by potential theory and a depth-linear eddy viscosity is employed in the turbulent boundary layer at the seabed. The derived bed stress is used to predict the sand-bed evolution. Laboratory experiments and corresponding numerical simulations for both high and low beach reflection are discussed. For weak reflection, the shear stress associated with the return current is found to be important. Partial simulation of a field record in Cape Cod Bay is also described. The dependence of bar morphology on sediment grain size is examined experimentally. In particular, new quantitative data on sandbar formation and sediment sorting on a bed of mixed colored sands of significantly different grain sizes under standing waves is presented to motivate future study.
DE: 3238 Prediction (3245, 4263)
DE: 3285 Wave propagation (0689, 2487, 4275, 4455, 6934)
DE: 4558 Sediment transport (1862)
DE: 4560 Surface waves and tides (1222)
DE: 4562 Topographic/bathymetric interactions
SC: Hydrology [H]
MN: 2007 Fall Meeting