Hostname: page-component-cd9895bd7-dk4vv Total loading time: 0 Render date: 2024-12-18T15:00:57.937Z Has data issue: false hasContentIssue false

On the excitation of long nonlinear water waves by a moving pressure distribution. Part 2. Three-dimensional effects

Published online by Cambridge University Press:  21 April 2006

C. Katsis
Affiliation:
Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
T. R. Akylas
Affiliation:
Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA

Abstract

The three-dimensional wave pattern generated by a moving pressure distribution of finite extent acting on the surface of water of depth h is studied. It is shown that, when the pressure distribution travels at a speed near the linear-long-wave speed, the response is governed by a forced nonlinear Kadomtsev-Petviashvili (KP) equation, which describes a balance between linear dispersive, nonlinear and three-dimensional effects. It is deduced that, in a channel of finite width 2w, three-dimensional effects are negligible if w [Lt ] h2/a, a being a typical wave amplitude; in such a case the governing equation reduces to the forced Korteweg-de Vries equation derived in previous studies. For aw/h2 = O(1), however, three-dimensional effects are important; numerical calculations based on the KP equation indicate that a series of straight-crested solitons are radiated periodically ahead of the source and a three-dimensional wave pattern forms behind. The predicted dependencies on channel width of soliton amplitude and period of soliton formation compare favourably with the experimental results of Ertekin, Webster & Wehausen (1984). In a channel for which aw/h2 [Gt ] 1, three-dimensional, unsteady disturbances appear-ahead of the pressure distribution.

Type
Research Article
Copyright
© 1987 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Akylas, T. R. 1984 On the excitation of long nonlinear water waves by a moving pressure distribution. J. Fluid Mech. 141, 455466.Google Scholar
Baines, P. G. 1979 Observations of stratified flow over two-dimensional obstacles in fluid of finite depth. Tellus 31, 351371.Google Scholar
Baines, P. G. 1984 A unified description of two-layer flow over topography. J. Fluid Mech. 140, 127167.Google Scholar
Cole, S. L. 1985 Transient waves produced by flow past a bump, Wave Motion 7, 579587.Google Scholar
Cole, S. L. 1986 Transient waves produced by a moving pressure distribution, Q. Appl. Maths, (in press).Google Scholar
Ektekin, R. C. 1984 Soliton generation by moving disturbances in shallow water: Theory, computation and experiment. Doctoral dissertation, University of California, Berkeley.
Eetekin, R. C., Webster, W. C. & Wehausen, J. V. 1984 Ship-generated solitons, Proc. 15th Symp. Naval Hydrodyn. pp. 115. National Academy of Sciences, Washington, DC.
Ertekin, R. C., Webster, W. C. & Wehausen, J. V. 1986 Waves caused by a moving disturbance in a shallow channel of finite width, J. Fluid Mech. 169, 275292.Google Scholar
Grimshaw, R. H. J. & Smyth, N. 1985 Resonant flow of a stratified fluid over topography. The University of Melbourne, Dept Maths Res. Rep. no. 141985.Google Scholar
Huang, D.-B., Sibul, O. J., Webster, W. C., Wehausen, J. V., Wu, D.-M. & Wu, T. Y. 1982 Ships moving in the transcritical range. Proc. Conf. on Behaviour of Ships in Restricted Waters. (Varna, Bulgaria) vol. 2, pp. 26-1––26-10.
Inui, T. 1936 On deformation, wave patterns and resonance phenomenon of water surface due to a moving disturbance, I. Proc. Phys.-Math. Soc. Japan 18, 6098.Google Scholar
Kadomtsev, B. B. & Petviashvili, V. I. 1970 On the stability of solitary waves in weakly dispersing media, Sov. Phys. Dokl. 15, 539541.Google Scholar
Katsis, C. 1986 An analytical and numerical study of certain three-dimensional nonlinear wave phenomena. Doctoral dissertation, Department of Mechanical Engineering, MIT.
Lee, S.-J. 1985 Generation of long water waves by moving disturbances. Doctoral dissertation, California Institute of Technology.
Lighthill, M. J. 1978 Waves in Fluids. Cambridge University Press.
Mei, C. C. 1976 Flow around a thin body moving in shallow water, J. Fluid Mech. 77, 737751.Google Scholar
Mei, C. C. 1986 Radiation of solitons by slender bodies advancing in a shallow channel. J. Fluid Mech. 162, 5367.Google Scholar
Miles, J. W. 1977 Diffraction of solitary waves. Z. angew. Math. Phys. 28, 889902.Google Scholar
Miles, J. W. 1986 Stationary, transcritical channel flow. J. Fluid Mech. 162, 489499.Google Scholar
Redekopp, L. G. 1980 Similarity solutions of some two-space-dimensional nonlinear wave evolution equations, Stud. Appl. Maths 63, 185207.Google Scholar
Taha, T. R. & Ablowitz, M. J. 1984 Analytical and numerical aspects of certain nonlinear evolution equations III. Numerical, Korteweg-de Vries equation. J. Comp. Phys. 55, 231253.Google Scholar
Ursell, F. 1960 On Kelvin's ship-wave pattern. J. Fluid Mech. 8, 418431.Google Scholar
Wu, D.-M. & Wu, T. Y. 1982 Three-dimensional nonlinear long waves due to moving surface pressure. Proc. 14th Symp. Naval Hydrodyn. pp. 103129. National Academy of Sciences. Washington, DC.
Wu, T. Y. 1986 Periodic generation of solitons by steady moving bodies. Proc. First International Workshop on Water Waves and Floating Bodies. Cambridge, MA.