Abstract
Local equilibrium of winds and wind-waves is discussed as a basis for research of the drag coefficient of the water surface as well as for the spectral growth of wind-waves. This hypothesis assumes, in a narrow sense, that statistical properties are determined from four physical quantities, which represent winds and wind-waves: the friction velocityu *, the gravitational accelerationg, the powerE of the surface displacement, and the peak frequencyω p of a wind-wave spectrum. Then one has only one nondimensionalcontrol parameter, which may be either the wave age or wave nonlinearity (slope) of dominant waves. In a wide-sense, one can take into account viscosity and surface tension in terms of one more additional parameter by virtue of the virtual invariance of those material constants; that parameter describes the scale ratio between dominant waves and the short waves for which viscosity or surface tension is important. A unified expression for the roughness height according to this hypothesis turns out to include Charnock's and Toba's formulas as special cases. On the basis of a preliminary analysis of the experimental data, a new empirical formula is proposed.
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Masuda, A., Kusaba, T. On the local equilibrium of winds and wind-waves in relation to surface drag. Journal of the Oceanographical Society of Japan 43, 28–36 (1987). https://doi.org/10.1007/BF02110631
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DOI: https://doi.org/10.1007/BF02110631