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Long bed waves in tidal seas: an idealized model

Published online by Cambridge University Press:  25 September 2009

PAOLO BLONDEAUX ,
HUIB E. DE SWART  and
GIOVANNA VITTORI
PAOLO BLONDEAUX*
Affiliation:
Department of Civil, Environmental and Architectural Engineering, Genoa University, Via Montallegro 1, 16145 Genova, Italy
HUIB E. DE SWART
Affiliation:
Institute for Marine and Atmospheric Research, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
GIOVANNA VITTORI
Affiliation:
Department of Civil, Environmental and Architectural Engineering, Genoa University, Via Montallegro 1, 16145 Genova, Italy
*
†Email address for correspondence: [email protected]
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Abstract

An idealized model is proposed to explain the appearance of the long bed waves that have been recently observed in shallow tidal seas. The model assumes that these bedforms grow due to tide–topography interaction. The water motion is described by means of the depth-averaged shallow water equations and the bottom evolution is governed by conservation of sediment mass. The sediment transport formulation includes a critical bottom stress below which no sediment moves. Also, anisotropic sediment transport, due to local bottom slopes in the longitudinal and transverse directions, is taken into account. A linear stability analysis of the flat bottom configuration reveals that different bottom patterns can emerge. In accordance with previous analyses, for strong tidal currents, the fastest growing modes are sand banks. However, if the tidal currents are elliptical and the maximum bottom stress is just above its threshold value for the initiation of sediment motion, the model shows the presence of further growing modes which resemble the long bed waves observed in the field.

Type
Papers
Information
Journal of Fluid Mechanics , Volume 636 , 10 October 2009 , pp. 485 - 495
Copyright
Copyright © Cambridge University Press 2009

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References

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