Wave–current interaction

In fluid dynamics, waveâ€"current interaction is the interaction between surface gravity waves and a mean flow. The interaction implies an exchange of energy, so after the start of the interaction both the waves and the mean flow are affected.

For depth-integrated and phase-averaged flows, the quantity of primary importance for the dynamics of the interaction is the wave radiation stress tensor.

Waveâ€"current interaction is also one of the possible mechanisms for the occurrence of rogue waves, such as in the Agulhas Current. When a wave group encounters an opposing current, the waves in the group may pile up on top of each other which will propagate into a rogue wave.

Classification

Peregrine (1976) identifies five major sub-classes within waveâ€"current interaction:

• interaction of waves with a large-scale current field, with slow â€" as compared to the wavelength â€" two-dimensional horizontal variations of the current fields;
• interaction of waves with small-scale current changes (in contrast with the case above), where the horizontal current varies suddenly, over a length scale comparable with the wavelength;
• the combined waveâ€"current motion for currents varying (strongly) with depth below the free surface;
• interaction of waves with turbulence; and
• interaction of ship waves and currents, such as in the ship's wake.

See also

• rip current

Footnotes

References

• Bretherton, F. P.; Garrett, C. J. R. (1968), "Wavetrains in inhomogeneous moving media", Proceedings of the Royal Society of London, Series A, Mathematical and Physical Sciences 302 (1471): 529â€"554, Bibcode:1968RSPSA.302..529B, doi:10.1098/rspa.1968.0034 
• Peregrine, D. H. (1976), "Interaction of water waves and currents", Advances in Applied Mechanics 16, Academic Press, pp. 9â€"117, ISBN 978-0-12-002016-4 
• Phillips, O. M. (1977), The dynamics of the upper ocean (2nd ed.), Cambridge University Press, ISBN 0-521-29801-6 
• Craik, A. D. D. (1988), Wave interactions and fluid flows, Cambridge University Press, ISBN 0-521-36829-4 
• Prandle, D. (1992), Dynamics and exchanges in estuaries and the coastal zone, Coastal and estuarine studies 40, American Geophysical Union, ISBN 0-87590-254-5 
• Jonsson, I. G. (1990), "Waveâ€"current interactions", in B. Le Méhauté and D. M. Hanes, Ocean Engineering Science, The Sea 9A, Wiley Interscience, pp. 65â€"120, ISBN 0-471-11543-6