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Generation of Ripple-Size Internal Waves on a Fluidized Seafloor

Research paper by Mostafa A. Foda

Indexed on: 01 Feb '99Published on: 01 Feb '99Published in: Journal of Engineering Mathematics



Abstract

Ripples produced on a fluidized seafloor have been observed in the field as well as in the laboratory. Because of their dynamic properties, they are sometimes referred to as transitional or ephemeral ripples, as they have been observed to go through cycles of forming and disappearing on the time scale of an individual wave period. The ripples also appear to go through a complex evolutionary sequence, occasionally leading to the spectacular event of sediment bursting from the seafloor. During bursting, loads of fluidized sediment will be ejected upward into the water column – in the form of intense sand plumes. Reproducing these ripples in the laboratory revealed that these ripples are actually a standing subharmonic internal wave on the water-sediment interface, produced by the water wave propagating above through an instability mechansim. In this paper an inviscid theory for the initial excitation of these dynamic ripples on a fluidized seafloor is presented.