Print Email Facebook Twitter The directional energy distribution of wind generated waves as inferred from stereophotographic observations of the sea surface Title The directional energy distribution of wind generated waves as inferred from stereophotographic observations of the sea surface Author Holthuijsen, L.H. Contributor Battjes, J.A. (promotor) Faculty Civil Engineering and Geosciences Department Hydraulic Engineering Date 1981-05-26 Abstract The objective of the present study is to determine characteristics of the directional energy distribution of wind generated waves on the basis of observations with a relatively high resolution. Approximately 75 observations of the above distribution are studied. They are selected from five spectra which are determined from stereophotographic observations of the sea surface. Three of these spectra were obtained in a so-called ideal generation situation. This is a situation where a homogeneous, stationary wind blows perpendicularly off a straight coast over deep water. The other two spectra were observed in similar situations. The difference with the ideal situation is for one spectrum that the wind was slanting across the coastline and for the other that the coastline was irregular. The observed distributions are compared with the cos²s (?/2)-model introduced by Longuet-Higgins et al. (1963). The differences between the observations and this model can be quantified due to the high resolution of the observations. It is found in the ideal situation that the model agrees well for most practical purposes with the observed distributions. In fact, the model is found to be highly consistent with those observations in the ideal situation for which a consistency analysis was carried out. In the other two situations it is found that the shape of the directional energy distribution is strongly influenced by the geometry of the upwind coastline. Thls suggests a directionally decoupled generation of the waves. The results of a simple parametric wave hindcasting model support this suggestion. The shape of the observed functional relationship between the width parameter s of the cos²s(?/2)-model and the wavenumber agrees fairly well with the shapes suggested by Mitsuyasu et al. (1975) and Hasselmann et al. (1980). Subject water wavesrandom wavesdirectional spectrastereo photo To reference this document use: http://resolver.tudelft.nl/uuid:4904e14d-3d63-4308-b839-92579ace3bce Part of collection Institutional Repository Document type doctoral thesis Rights (c) 1981 Holthuijsen, L.H. Files PDF Holthuijsen1981.pdf 3.44 MB Close viewer /islandora/object/uuid:4904e14d-3d63-4308-b839-92579ace3bce/datastream/OBJ/view