Research on Wind Wave Considering Nonlinear Dispersion Effect

Abstract

Understanding of the offshore wind wave status plays a guiding role in surrounding marine engineering constructions, marine traffic, sea farming, etc. Further study is beneficial to marine economy development, as well as to the academic value of wave theory. This paper primarily introduces the deduction of new wind wave growth relations. Firstly, a new relation formula between wave steepness and wave age was deduced by combining the 3/2 power law developed by Toba with the nonlinear dispersion relation deduced by Li, and by ignoring the effect of water depth. And when the higher-order term was ignored, the relation formula can be simplified as that based on linear dispersion. Secondly, based on the combination of this new relation formula with the significant wave energy balance equation, new wind wave growth relation formulae including the wave non-linear dispersion effect were deduced. When the deduced growth relation formulae were applied in offshore area of Jiangsu incorporating with Mitsuyasu’s empirical formula about the open sea fetch and wind speed, accurate open sea wave parameters of Jiangsu can be formulated by only considering one parameter, such as wind speed. Overall, as this methodology avoided the uncertainty about the fetch of open ocean and operation error during the calculation process, results gained from this report had higher accuracy than other published formulae, and results were validated by NCEP reanalyzing data of Jiangsu offshore area and other researches.