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Long-wave-induced flows in an unsaturated permeable seabed

Published online by Cambridge University Press:  14 August 2007

PHILIP L.-F. LIU ,
YONG SUNG PARK  and
JAVIER L. LARA
PHILIP L.-F. LIU
Affiliation:
School of Civil and Environmental Engineering, Cornell University, Ithaca, NY 14853, USA
YONG SUNG PARK
Affiliation:
School of Civil and Environmental Engineering, Cornell University, Ithaca, NY 14853, USA
JAVIER L. LARA
Affiliation:
School of Civil and Environmental Engineering, Cornell University, Ithaca, NY 14853, USA
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Abstract

We present both analytical and numerical solutions describing seepage flows in an unsaturated permeable seabed induced by transient long waves. The effects of compressibility of pore water in the seabed due to a small degree of unsaturation are considered in the investigation. To make the problem tractable analytically, we first focus our attention on situations where the horizontal scale of the seepage flow is much larger than the vertical scale. With this simplification the pore-water pressure in the soil column is governed by a one-dimensional diffusion equation with a specified pressure at the water–seabed interface and the no-flux condition at the bottom of the seabed. Analytical solutions for pore-water pressure and velocity are obtained for arbitrary transient waves. Special cases are studied for periodic waves, cnoidal waves, solitary waves and bores. Numerical solutions are also obtained by simultaneously solving the Navier–Stokes equations for water wave motions and the exact two-dimensional diffusion equation for seepage flows in the seabed. The analytical solutions are used to check the accuracy of the numerical methods. On the other hand, numerical solutions extend the applicability of the analytical solutions. The liquefaction potential in a permeable bed as well as the energy dissipation under various wave conditions are then discussed.

Type
Papers
Information
Journal of Fluid Mechanics , Volume 586 , 10 September 2007 , pp. 323 - 345
Copyright
Copyright © Cambridge University Press 2007

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