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Effects of wavelength ratio on wave modelling

Published online by Cambridge University Press:  26 April 2006

Jun Zhang
Affiliation:
Ocean Engineering Program, Department of Civil Engineering, Texas A & M University, College Station, TX 77843-3136, USA
Keyyong Hong
Affiliation:
Ocean Engineering Program, Department of Civil Engineering, Texas A & M University, College Station, TX 77843-3136, USA
Dick K. P. Yue
Affiliation:
Department of Ocean Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA

Abstract

The efficacy of perturbation approaches for short–long wave interactions is examined by considering a simple case of two interacting wave trains with different wavelengths. Frequency-domain solutions are derived up to third order in wave steepness using two different formulations: one employing conventional wave-mode functions only, and the other introducing a modulated wave-mode representation for the short-wavelength wave. For long-wavelength wave steepness and short-to-long wavelength ratio ε1 and ε3 respectively, the two results are shown to be identical for ε1 [Lt ] ε3 < 0.5. As ε1 approaches ε3, the conventional wave-mode approach converges slowly and eventually diverges for ε1 [Gt ] ε3. The loss of convergence is because the linear phase of conventional wave-mode functions is ineffective for modelling the modulated phase of the short wave. As expected, this difficulty can be removed by using a modulated wave-mode function for the short wave. On the other hand, for relatively large ε3 ∼O(1), the conventional wave-mode approach converges rapidly while the slowly varying interaction between the two waves cannot be accurately predicted by the present modulated wave-mode approach. These findings have important implications to (time-domain) numerical simulations of the nonlinear evolution of ocean wave fields, and suggest that a hybrid wave model employing both conventional (for large-ε3 interactions) and modulated (for small-ε3 interactions) wave-mode functions should be particularly effective.

Type
Research Article
Copyright
© 1993 Cambridge University Press

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References

Benney, D. J. 1962 Nonlinear gravity wave interactions. J. Fluid Mech. 14, 577589.Google Scholar
Brueckner, K. A. & West, B. J. 1988 Vindication of mode-coupled description of multiple scale water wave fields. J. Fluid Mech. 196, 585592.Google Scholar
Cohen, B. I., Watson, K. M. & West, B. J. 1976 Some properties of deep water solutions. Phys. Fluids 19, 345354.Google Scholar
Crawford, D. R., Lake, B. M., Saffman, P. G. & Yuen, H. C. 1981 Stability of weakly nonlinear deep-water waves in two and three dimensions. J. Fluid Mech. 105, 177191.Google Scholar
Dommermuth, D. G. & Yue, D. K. P. 1987 A high-order spectral method for the study of nonlinear gravity waves. J. Fluid Mech. 184, 267288.Google Scholar
Hasselmann, K. 1962 On the non-linear energy transfer in a gravity-wave spectrum. Part 1. General theory. J. Fluid Mech. 12, 481500.Google Scholar
Holliday, D. 1977 On nonlinear interactions in a spectrum of inviscid gravity–capillary surface waves. J. Fluid Mech. 84, 737749.Google Scholar
Longuet-Higgins, M. S. 1987 The propagation of short surface waves on longer gravity waves. J. Fluid Mech. 177, 293306.Google Scholar
Longuet-Higgins, M. S. & Phillips, O. M. 1962 Phase velocity effects in tertiary wave interactions. J. Fluid Mech. 12, 333336.Google Scholar
Longuet-Higgins, M. S. & Stewart, R. W. 1960 Changes in the form of short gravity waves on long waves and tidal currents. J. Fluid Mech. 8, 565583.Google Scholar
Milder, D. M. 1990 The effects of truncation on surface-wave Hamiltonians. J. Fluid Mech. 216, 249262.Google Scholar
Phillips, O. M. 1960 On the dynamics of unsteady gravity of finite amplitude. Part 1. The elementary interactions. J. Fluid Mech. 9, 193217.Google Scholar
Phillips, O. M. 1981 The dispersion of short wavelets in presence of a dominant long wave. J. Fluid Mech. 107, 465485.Google Scholar
Watson, K. M. & West, B. J. 1975 A transport-equation description of nonlinear ocean surface wave interactions. J. Fluid Mech. 70, 815826.Google Scholar
West, B. J. 1981 On the Simpler Aspects of Nonlinear Fluctuating Deep Water Gravity Waves. Lecture Notes in Physics, vol. 146. Springer.
West, B. J., Brueckner, K. A. & Janda, R. S. 1987 A new numerical method for surface hydrodynamics. J. Geophys. Res. 92, 1180311824.Google Scholar
West, B. J., Watson, K. M. & Thomson, A. J. 1974 Mode coupling description of ocean wave dynamics. Phys. Fluids 17, 10591067.Google Scholar
Zakharov, V. E. 1968 Stability of periodic waves of finite amplitude on the surface of a deep fluid. J. Appl. Mech. Tech. Phys. 9, 190194.Google Scholar
Zhang, J. 1991 Fourth-order Lagrangian of short waves riding on long waves. Phys. Fluids A 3, 30073013.Google Scholar
Zhang, J. & Melville, W. K. 1990 Evolution of weakly nonlinear short waves riding on long gravity waves. J. Fluid Mech. 214, 321346.Google Scholar
Zhang, J. & Melville, W. K. 1992 On the stability of weakly nonlinear short waves on finite-amplitude long gravity waves. J. Fluid Mech. 243, 5172.Google Scholar