SWAN
Simulating WAves Nearshore
In many engineering studies, knowledge of the operational or of the extreme wave conditions in coastal waters (which may include estuaries, tidal inlets, barrier islands with tidal flats, channels etc.) is required. To obtain realistic estimates of random, short-crested wind-generated waves in such conditions for a given bottom topography, wind field, water level and current field, the numerical wave model SWAN which is a model of the Delft university of Technology can be used. This SWAN model is a third-generation stand-alone (phase-averaged) wave model for the simulation of waves in waters of deep, intermediate and finite depth. It is also suitable for use as a wave hindcast model.
In order to enable an efficient and a direct coupling between e.g. circulation models (wave driven currents) and sediment transport models (stirring by wave breaking), the SWAN model is presently also integrated under the numerical Delft3D model. SWAN can be applied to:
- Nearshore wave modelling for harbour and offshore installation design
- Coastal development and management
- Wave hindcasting
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Computed significant wave height pattern and mean direction of energy transport (denoted with vectors) in the Haringvliet (a branch of the Rhine estuary in the south-west of the Netherlands).
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Computed wave spectra at 23.00 UTC and observations (scattered around 23.00 UTC) on October 12, 1982 at three stations (1, 5 and 8). Note the differences in energy density scale in the panels.
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processes
SWAN simulates the following physical phenomena:
- Wave propagation in time and space, shoaling, refraction due to current and depth, frequency shifting due to currents and nonstationary depth.
- Wave generation by wind.
- Nonlinear wave-wave interactions (both quadruplets and triads).
- Whitecapping, bottom friction, and depth-induced breaking.
- Blocking of waves by current.
Note that diffraction is not explicitly modelled in SWAN but diffraction effects can be simulated by applying directional spreading of the waves. Reflections are also not included in SWAN. In strongly diffracting situations or situations with significant reflection effects the SWAN model should be coupled with the Deltares wave penetration model PHAROS. This coupling has recently been implemented for use in wave disturbance modelling in harbours.
links
more information
current release: 40.51, August 2006
For more information please contact delftwaves.info@deltares.nl.
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