Waves

The Delft3D suite consists of various components to model the particular physics of the water system, such as the hydrodynamics, morphology and water quality. The Delft3D Wavecomponent can be used to simulate the propagation and transformation of random, short-crested, wind generated waves in coastal waters which may extend to estuaries, tidal inlets, barrier islands with tidal flats, channels etc.

The Delft3D-Wave module consists of a slightly adapted version of the open source model SWAN and a shell  allowing for interaction with Delft3D modules like Delft3D-FLOW and providing additional options for model input like "spiderweb windfields". SWAN was developed by Delft University of Technology (TUD) with support of the Office of Naval Research (ONR). It is managed and maintained by TUD with funding of the Dutch Ministry of Public Works. TUD releases authorized versions of SWAN in the public domain as open source code under the GNU GPL license. Further information about SWAN can be found here. For detailed information about the Delft3D-Wave module and the adapted SWAN version (including usage) reference is made to the Delft3D-Wave manual or you can ask your question on this forum. It should be noted that there are some differences between the authorized SWAN version and the adapted version in Delft3D-Wave: the adapted version writes more decimal positions and other error messages to the output file.

The SWAN model is applicable in deep, intermediate and shallow waters and the spatial model grid may cover any model surface area of up to more than 50 km by 50 km.

The added value of Delft3D Wave is the capability of Delft3D Hydrodynamics, Morphology and Waves to perform a so-called online calculation, in which information is transferred from Flow and Morphology to Wave and back again. This online coupling allows for the simulation of complex water systems in which flow-wave (wave currents interaction as well as wave setup) or flow-wave-morphology (effect of radiation stress on sediment transport and seabed changes) are important.

SWAN is a so-called phase-averaged wave model which is less or not applicable in regions where complex phenomena occur within relatively short distances, e.g. near coastal structures or steep sloping beaches, and within harbors. For those areas phase-resolving modelsare required to obtain more accurate wave predictions. Examples of these models are Boussinesq-type models and Multi-layer models.

In practice Delft3D-Wave (in combination with other modules) is used to transform offshore information such as wind speed statistics to nearshore wave conditions, or more concrete, hydraulic loads on revetments, dune retreat, resulting ship motion, etc. Several models and techniques are required for this transfer, that are coupled in a so-called coastal engineering platform.