Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/14603
Title: Numerical simulation of large-scale waves and currents
Authors: ZHANG DAN
Keywords: Wind waves, Ocean current, 3D radiation stresses, Wave-current interaction, Princeton Ocean Model, SWAN
Issue Date: 7-Mar-2005
Source: ZHANG DAN (2005-03-07). Numerical simulation of large-scale waves and currents. ScholarBank@NUS Repository.
Abstract: For the past decades, wave models and ocean circulation models have been developed separately. Wave models dona??t recognize the vertical structure of ocean currents and ocean models neglect the effect of waves. However, the waves and ocean currents can interact in many ways, one of which is through radiation stresses. The conventional radiation stresses (2D) are defined in the vertically integrated form. The coupling of wave model and ocean circulation model is usually accomplished by including the depth-averaged radiation stresses as the forcing term in the momentum equation. Unfortunately, 2D radiation stresses can not properly represent the effect of waves on currents.In this thesis, expressions for depth-dependent radiation stresses (3D) are derived in the Cartesian coordinates on the basis of linear wave theory. After vertical integration, these expressions revert to the conventional 2D radiation stresses. In viewpoint of physics, the effect of waves varies along the water depth, especially in deep water. However, the conventional radiation stresses fail to reflect this phenomenon. In contrast, 3D radiation stresses are able to explain the wave-current interaction. The newly derived 3D radiation stresses are suitable for simulating the effect of waves on currents, such as wind-induced circulation in a water basin, wave induced cross-shore currents and long-shore currents. The performance of the numerical model is demonstrated by comparison with theoretical results, experimental data and conceptual analysis. They display a favorable match. It is shown that the turbulence needs to be considered when we study wave-induced currents in the nearshore zone. Compared with 2D radiation stresses, 3D radiation stresses have larger effect on ocean currents. More work should be carried out about the wave-current interaction through depth-dependent radiation stresses.
URI: http://scholarbank.nus.edu.sg/handle/10635/14603
Appears in Collections:Master's Theses (Open)

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