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Particle trajectories in nonlinear gravity–capillary waves

Published online by Cambridge University Press:  20 April 2006

S. J. Hogan
Affiliation:
Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Silver Street, Cambridge CB3 9EW Permanent address: Mathematical Institute, University of Oxford, St Giles, Oxford OX1 3LB.

Abstract

The trajectories of surface and subsurface particles of nonlinear gravity–capillary waves are calculated. Surface tension is found to have a small effect on the trajectories and drift velocity of pure gravity waves (down to 20 cm in length). On the other hand, pure capillary wave trajectories can be considerably altered even when the influence of gravity is small (waves of up to 2 cm in length). When the restoring forces are of comparable magnitude, some remarkable trajectories are possible, containing one or more subloops. Overall, the influence of increased surface tension is to increase the relative horizontal distance travelled by a particle, as well as the magnitude of the time-averaged drift velocity ratio at the surface and, as far as short waves are concerned, its penetration depth.

These results can have implications for steep waves where parasitic capillaries are generated and for observations of the wind-drift current.

Type
Research Article
Copyright
© 1985 Cambridge University Press

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