HR: 16:30h
AN: OS24A-03    [Abstracts]
TI: Water Waves Over Non-Rigid Muddy Bottoms
AU: * Alam, M
EM: alam@mit.edu
AF: Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, cambridge, MA 02139, United States
AU: Liu, Y
EM: yuming@mit.edu
AF: Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, cambridge, MA 02139, United States
AU: Yue, D
EM: yue@mit.edu
AF: Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, cambridge, MA 02139, United States
AB: The phenomenon of the wave-attenuation over muddy sea beds is considered invoking a mass-spring-damper bottom model. Reports of observed strong dissipation for surface waves traveling over muddy bottoms in Gulf of Mexico and Indian ocean inflamed a great deal of attention in the late past century. Numerous models including two-layer models with Newtonian and/or non-Newtonian lower layer, porous ground models, and bottom friction models were developed. Considering the limitations of existing models due to the complicated nature of the mud, we develop a visco- elastic bottom model where the inertia, elasticity coefficient and the damping coefficient are dependent on the mud properties. The proposed system admits up to four eigen-mode solutions with oscillatory and exponentially decaying parts. Contrary to all existing models, and supportive to some recent observations (see for example Sheremet & Stone 2003; Sheremet 2005), the model explains the possibility of larger energy decay rate for higher incident wave frequencies. Amenable to numerical simulations, the model is converted to the classic flat bottom problem with a modified free surface boundary condition. An efficient numerical scheme based on the higher-order spectral method is adopted, and general cases including the evolution of broadband incident waves is studied. The effect of weak nonlinearity is considered numerically and theoretically. \noindent{\sc Sheremet, A. & Stone, G.~W.} 2003 Observation of nearshore wave dissipation over muddy sea beds. Journal of Geophysical Research\/ 108~(C11), 21(1--11).
{\sc Sheremet, A., Mehta-A.J. Liu B. Stone~G.W.} 2005 Wave-sediment interaction on a muddy inner shelf during hurricane claudette. ESTUARINE COASTAL AND SHELF SCIENCE\/ 63~(1-2), 225--233.
DE: 4562 Topographic/bathymetric interactions
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting