Release Time:2019-03-09  Hits:

Indexed by: Journal Article

Date of Publication: 2014-12-01

Journal: COASTAL ENGINEERING

Included Journals: Scopus、EI、SCIE

Volume: 94

Page Number: 23-32

ISSN: 0378-3839

Key Words: Shallow water; Random waves; Nonlinear interaction; Wavelet-based bispectrum; Parameterization

Abstract: Investigation of the bottom slope effects on the nonlinear transformation of irregular waves, which are generated based on JONSWAP spectra, is carried out in a physical wave flume with three slopes (beta = 1/15,1/30, 1/45). The slope effects on the estimation of representative wave height are examined first. To obtain a better estimation of wave height, the slope effect should be considered when slope is larger than 1/30. The nonlinear parameters (bicoherence, skewness and asymmetry) are estimated by using the wavelet-based bispectrum, and the empirical formulae regarding these nonlinear parameters as a function of the local Ursell number are derived based on the present data measured on each slope. The results indicate that the slopes have a negligible effect on the variations of the skewness. The fitted coefficients of the formulae for the other parameters on slope beta = 1/15 are clearly different from the results on the slopes beta = 1/30 and 1/45, indicating that slope influence on the parameterization cannot be ignored when beta > 1/30. Hence, new formulae considering the slope effect are presented. Furthermore, the empirical formulae for the data in surf zone are recommended. (C) 2014 Elsevier B.V. All rights reserved.