The equilibrium range in the spectrum of wind-generated waves
- 1 May 1958
- journal article
- research article
- Published by Cambridge University Press (CUP) in Journal of Fluid Mechanics
- Vol. 4 (04) , 426-434
- https://doi.org/10.1017/s0022112058000550
Abstract
Consideration of the structure of wind-generated waves when the duration and fetch of the wind are large suggests that the smaller-scale components of the wave field may be in a condition of statistical equilibrium determined by the requirements for attachment of the crests of the waves. A dimensional analysis, based upon the idea of an equilibrium range in the wave spectrum, shows that for large values of the frequency ω, the spectrum Φ(ω) is of the form where α is an absolute constant. The instantaneous spatial spectrum Ψ (k) is proportional to k−4 for large wave numbers k, which is consistent with the observed occurrence of sharp crests in a well-developed sea, and the loss of energy from the wave system to turbulence and heat is proportional to , where ρw is the water density and u the friction velocity of the wind at the surface. This prediction of the form of Φ(ω) for large ω with α = 7·4×10−3, agrees well with measurements made by Burling (1955).Keywords
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