Wind wave modelling in shallow water: with application to the southern North Sea
Increased marine activities, particularly in areas of off-shore exploitation and coastal development, have created an urgent need for improved knowledge of wave conditions in the shallow near-shore regions. In this work, objectives have been made to investigate the effects of bottom friction, depth-induced wave breaking, and tidal motions on the wave evolution in shallow water, and to apply the wave model (WAM Cycle 4) to the Belgian coastal waters. Firstly, the effects of different bottom friction formulations on the energy balance equation were quantitatively investigated for fetch-limited s... Mehr ...
Verfasser: | |
---|---|
Dokumenttyp: | doctoralThesis |
Erscheinungsdatum: | 1995 |
Schlagwörter: | Bottom friction / Modelling / Numerical models / Shallow water / Wave breaking / Wave predicting / Wind waves / ANE / Belgium / Belgian Coast |
Sprache: | Englisch |
Permalink: | https://search.fid-benelux.de/Record/base-28496139 |
Datenquelle: | BASE; Originalkatalog |
Powered By: | BASE |
Link(s) : | https://www.vliz.be/imisdocs/publications/226695.pdf |
Increased marine activities, particularly in areas of off-shore exploitation and coastal development, have created an urgent need for improved knowledge of wave conditions in the shallow near-shore regions. In this work, objectives have been made to investigate the effects of bottom friction, depth-induced wave breaking, and tidal motions on the wave evolution in shallow water, and to apply the wave model (WAM Cycle 4) to the Belgian coastal waters. Firstly, the effects of different bottom friction formulations on the energy balance equation were quantitatively investigated for fetch-limited shallow water conditions. It was found that the formulation of the bottom friction dissipation has a quite significant effect on the energy balance at shallower water depths. Among the five original formulations for the bottom friction dissipation investigated (i.e., an empirical expression based on the JONSWAP experiment (Hasselmann et al., 1973), three expressions based on the drag law turbulent friction model (Hasselmann and Collins, 1968; Collins, 1972; Madsen et al., 1988a) and one based on the eddy viscosity friction model (Weber, 1991a), a difference as big as 70% for the total energy was reported for a water depth of 15 m and a wind friction velocity of 0.71 ms¯¹. It is revealed that the whitecapping dissipation is dominant in shallow water. The contribution of bottom friction varies clearly with depth, and also from formulation to formulation. The role of bottom friction dissipation becomes more significant as the water becomes shallower. Secondly, it has been proven mathematically and numerically that in shallow water cases, the scaling ability of the energy growth curves with the air friction velocity is model-dependent. The growth curves from the drag law models with a fixed dissipation coefficient Cƒ, scale with the air friction velocity U a *. The drag law model with a dynamically changing friction factor, the empirical formulation and eddy viscosity model do not scale with the wind friction velocity U a *. It ...