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The modulation of short gravity waves by long waves or currents

Published online by Cambridge University Press:  17 February 2009

R. Grimshaw
Affiliation:
School of Mathematics, University of New South Wales, P.O. Box 1, Kensington, NSW 2033, Australia.
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Abstract

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The modulation of short gravity waves by long waves or currents is described for the situation when the flow is irrotational and when the short waves are described by linearised equations. Two cases are distinguished depending on whether the basic flow can be characterised as a deep-water current, or a shallow-water current. In both cases the basic flow has a current which has finite amplitude, while in the first case the free surface slope of the basic flow can be finite, but in the second case is small. The modulation equations are the local dispersion relation of the short waves, the kinematic equation for conservation of wave crests and the wave action equation. The results incorporate and extend the earlier work of Longuet-Higgins and Stewart [10, 11].

Type
Research Article
Copyright
Copyright © Australian Mathematical Society 1988

References

[1]Andrews, D. G. and McIntyre, M. E., “An exact theory of nonlinear waves on a Lagrangian mean-flow”, J. Fluid Mech. 89 (1978), 609646.CrossRefGoogle Scholar
[2]Andrews, D. G. and McIntyre, M. E., “On wave-action and its relatives”, J. Fluid Mech. 89 (1978), 647664.CrossRefGoogle Scholar
[3]Bretherton, F. P. and Garrett, C. J. R., “Wavetrains in inhomogeneous moving media”, Proc. Roy. Soc. London Ser. A 302 (1969), 539554.Google Scholar
[4]Craik, A. D. D., “Interaction of a short-wave field with a dominant long wave in deep water: derivation from Zakharov's spectral formulation”, J. Austral. Math. Soc. Ser. B 29 (1988), 430439.CrossRefGoogle Scholar
[5]Garrett, C. J. R., “On the interaction between internal gravity waves and a shear flow”, J. Fluid Mech. 34 (1968), 711720.CrossRefGoogle Scholar
[6]Grimshaw, R., “Mean flows induced by internal gravity wave packets propagating in a shear flow”, Philos. Trans. Roy. Soc. London Ser A 292 (1979), 391417.Google Scholar
[7]Grimshaw, R., “Wave action and wave-mean flow interaction, with application to stratified shear flows”, Ann. Rev. Fluid Mech. 16 (1984), 1144.CrossRefGoogle Scholar
[8]Hasselman, D. E., “The high wavenumber instabilities of a Stokes wave”, J. Fluid Mech. 93 (1979), 491499.CrossRefGoogle Scholar
[9]Le Blond, P. H. and Mysak, L. A., Waves in the ocean, (Elsevier, Amsterdam, 1978).Google Scholar
[10]Longuet-Higgins, M. S. and Stewart, R. W., “Changes in the form of short gravity waves on long waves and tidal currents”, J. Fluid Mech. 8 (1960), 565583.CrossRefGoogle Scholar
[11]Longuet-Higgins, M. S. and Stewart, R. W., “The changes in amplitude of short gravity waves on steady non-uniform currents”, J. Fluid Mech. 10 (1961), 529549.CrossRefGoogle Scholar
[12]Longuet-Higgins, M. S., “Surface wave interactions”, 9th. Australasian Fluid Mechanics Conference, (1986) 29–34.Google Scholar
[13]Longuet-Higgins, M. S., “The propagation of short surface waves on longer gravity waves”, J. Fluid Mech. 177 (1987), 293306.CrossRefGoogle Scholar
[14]Mei, C. C., The applied dynamics of ocean surface waves, (Wiley, New York, 1983).Google Scholar
[15]Peregrine, D. H. and Thomas, G. P., “Finite-amplitude deep-water waves on currents”, Philos. Trans. Roy. Soc. Ser. A 292 (1979), 371390.Google Scholar
[16]Phillips, O. M., “The dispersion of short wavelets in the presence of a dominant long wave”, J. Fluid Mech. 107 (1981), 465485.CrossRefGoogle Scholar
[17]Whitham, G. B., “Non-linear dispersion of water waves”, J. Fluid Mech. 27 (1967), 309412.CrossRefGoogle Scholar
[18]Whitham, G. B., Linear and nonlinear waves, (Wiley, New York, 1974).Google Scholar