A Volume of Fluid Model for Surf and Swash Zones
Abstract
Numerical modeling of nearshore waves and currents is necessary for forecasting hydrodynamic conditions and sediment transport which are used to predict erosion and accretion patterns of the nearshore profile. A typically used hydrodynamic model can be derived from the one-dimensional depth averaged non-linear shallow water equations (NLSWE). While this formulation has been shown to match field and laboratory data well, simplifications in the governing equations restrict the applicability of the model. For instance, the shallow water assumption means that separate models are required to shoal waves from deep water through the swash zone. Further, the depth-averaged nature yields no information regarding the vertical velocity profile and the boundary layer structure, which can be used to estimate the time dependent bed shear stress needed for sediment transport formulations. To overcome some of the drawbacks to the depth-averaged NLSWE, a 2D (x,z) volume of fluid model derived from the full Navier-Stokes equations has been modified for predicting sea surface elevations and depth dependent fluid velocities across the surf and swash zones. The volume of fluid approach discretizes the model domain into individual fluid volumes and calculates the appropriate force balances in each control volume and the flux of water across each control surface. Comparisons to laboratory data collected in a wave basin show excellent predictive skill for the sea surface elevations, while prediction of cross-shore fluid velocities suffers from over-prediction during the passage of broken waves. Model/data comparisons and model development including an upgrade from a constant eddy viscosity to a 2-equation turbulence closure scheme will be discussed.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2002
- Bibcode:
- 2002AGUFMOS71A0250P
- Keywords:
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- 4546 Nearshore processes