HR: 17:00h
AN: OS14B-05    [Abstracts]
TI: Vertical Distribution of Radiation Stress for Non-linear Shoaling Waves
AU: * Webb, B M
EM: bwebb@coastal.ufl.edu
AF: University of Florida, Department of Civil and Coastal Engineering 365 Weil Hall, Gainesville, FL 32611 United States
AU: Slinn, D N
EM: slinn@coastal.ufl.edu
AF: University of Florida, Department of Civil and Coastal Engineering 365 Weil Hall, Gainesville, FL 32611 United States
AB: The flux of momentum directed shoreward by an incident wave field, commonly referred to as the radiation stress, plays a significant role in nearshore circulation and, therefore, has a profound impact on the transport of pollutants, biota, and sediment in nearshore systems. Having received much attention since the seminal work of Longuet-Higgins and Stewart in the early 1960's, use of the radiation stress concept continues to be refined and evidence of its utility is widespread in literature pertaining to coastal and ocean science. A number of investigations, both numerical and analytical in nature, have used the concept of the radiation stress to derive appropriate forcing mechanisms that initiate cross-shore and longshore circulation, but typically in a depth-averaged sense due to a lack of information concerning the vertical distribution of the wave stresses. While depth-averaged nearshore circulation models are still widely used today, advancements in technology have permitted the adaptation of three-dimensional (3D) modeling techniques to study flow properties of complex nearshore circulation systems. It has been shown that the resulting circulation in these 3D models is very sensitive to the vertical distribution of the nearshore forcing, which have often been implemented as either depth-uniform or depth-linear distributions. Recently, analytical expressions describing the vertical structure of radiation stress components have appeared in the literature (see Mellor, 2003; Xia et al., 2004) but do not fully describe the magnitude and structure in the region bound by the trough and crest of non-linear, propagating waves. Utilizing a three-dimensional, non-linear, numerical model that resolves the time-dependent free surface, we present mean flow properties resulting from a simulation of Visser's (1984, 1991) laboratory experiment on uniform longshore currents. More specifically, we provide information regarding the vertical distribution of radiation stress components ($S_{xx}$ and $S_{xy}$) resulting from obliquely incident, non-linear shoaling waves. Vertical profiles of the radiation stress components predicted by the numerical model are compared with published analytical solutions, expressions given by linear theory, and observations from an investigation employing second-order cnoidal wave theory.
DE: 4255 Numerical modeling
DE: 4546 Nearshore processes
DE: 4558 Sediment transport
DE: 3020 Littoral processes
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting