Coupled dynamics of interfacial waves and bed forms in fluid muds over erodible seabeds in oscillatory flows
MetadataShow full item record
Recent field investigations of the damping of ocean surface waves over fluid muds have revealed waves on the interface between the thin layer of fluid mud and the overlying much thicker column of clear water, accompanied by bed forms on the erodible seabed beneath the fluid mud. The frequencies and wavelengths of the observed interfacial waves are qualitatively consistent with the linear dispersion relationship for long interfacial waves, but the forcing mechanism is not known. To understand the forcing, a linear model is proposed, based on the layer-averaged hydrostatic equations for the fluid mud, together with the Meyer-Peter-Mueller equation for the sediment transport within the underlying seabed, both subject to oscillatory forcing by the surface waves. If the underlying seabed is nonerodible and flat, the model indicates parametric instability to interfacial waves, but the threshold for instability is not met by the observations. If the underlying seabed is erodible, the model indicates that perturbations to the seabed elevation in the presence of the oscillatory forcing create interfacial waves, which in turn produce stresses within the fluid mud that force a net transport of sediment within the seabed toward the bed form crests, thus causing growth of both bed forms and interfacial waves. The frequencies, wavelengths, and growth rates are in qualitative agreement with the observations. A competition between mixing created by the interfacial waves and gravitational settling might control the thickness, density, and viscosity of the fluid muds during periods of strong forcing.
© The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Journal of Geophysical Research: Oceans 120 (2015): 5698–5709, doi:10.1002/2015JC010872.
Suggested CitationJournal of Geophysical Research: Oceans 120 (2015): 5698–5709
The following license files are associated with this item:
Except where otherwise noted, this item's license is described as Attribution-NonCommercial-NoDerivatives 4.0 International
Showing items related by title, author, creator and subject.
Geophysical fluid dynamics : notes on the 1960 Summer Study Program in Geophysical Fluid Dynamics at the Woods Hole Oceanographic Institution Spiegel, E. A. (Woods Hole Oceanographic Institution, 1960)
Young, Bill; Fauve, Stephan; DeRemer, Barbara Ewing; Meacham, Stephen P. (Woods Hole Oceanographic Institution, 1991-09)The GFD program in 1991 focused on pattern forming processes in physics and geophysics. The pricipallecturer, Stephan Fauve, discussed a variety of systems, including our old favorite, Rayleigh-Bénard convection, but ...
Veronis, George; Mellor, Florence K. (Woods Hole Oceanographic Institution, 1982-11)The (Lagrangian) motion of a fluid particle was contrasted with the (Eulerian) flow past a fixed point in space during this twenty-fourth summer program in geophysical fluid dynamics at the Woods Hole Oceanographic Institution.