intro story Coast / Estuary

Coast / Estuary

Coastal systems are among the most dynamic physical systems on earth and are subject to a large variety of forces. The morphodynamic changes occurring to coastlines worldwide are of great interest and importance. These changes occur as a result of the erosion of sediments, its subsequent transport as bed load or suspended load, and eventual deposition. 
 
Estuaries are partly enclosed water bodies that have an open connection to the coast. Estuaries generally have one or more branching channels, intertidal mudflats and/or salt marshes. Intertidal areas are of high ecological importance and trap sediments (sands, silts, clays and organic matter).
Within the Delft3D modelling package a large variation of coastal and estuarine physical and chemical processes can be simulated. These include waves, tidal propagation, wind- or wave-induced water level setup, flow induced by salinity or temperature gradients, sand and mud transport, water quality and changing bathymetry (morphology). Delft3D can also be used operationally e.g. storm, surge and algal bloom forecasting. 
 
On this discussion page you can post questions, research discussions or just share your experience about modelling coastal and/or estuarine systems with Delft3D FM. 
 

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Sub groups
D-Flow Flexible Mesh
DELWAQ
Cohesive sediments & muddy systems

 

 

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Non-physical wave directions at low frequencies

JH
Julia Hopkins, modified 7 Years ago.

Non-physical wave directions at low frequencies

Youngling Posts: 14 Join Date: 1/1/13 Recent Posts
Hello,

I have been working with Delft3D-WAVE as a stand-alone to model the wave climate of a tidal inlet, and have been running into some conceptual issues with SWAN's computational accuracy at low wave frequencies.

Specifically, I am looking at a wave field calculated over planar bathymetry and initialized with a uniform current (conditions simplified for debugging). The resulting 1D directional spectra shows the mean direction of waves at low frequencies crossing the shore-normal direction. In other words, if shore-normal is 180 deg then the mean directions of waves with an initial direction of 200 deg on the boundary do not cross 180 deg (physically reasonable) if their frequencies are greater than the peak frequency. However, the direction of waves with lower frequencies than the peak frequency do cross 180 deg (not physically reasonable).

Does anyone have any idea why the waves with frequencies below the peak frequency appear to turn too much as they shoal on a planar beach?

Thank you for your thoughts. They are very much appreciated.