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. 




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



Message Boards

I am wondering if I understand the governing equation correctly ?

Peng Dai, modified 2 Years ago.

I am wondering if I understand the governing equation correctly ?

Padawan Posts: 59 Join Date: 8/2/12 Recent Posts

In D3D user manual (refer to the Version: 3.15), in the subsection 9.3.1 hydrodynamic equations, the continuity equation uses the depth-averaged velocity, i.e. capitalized U and V (eq.9.3). The momentum equation uses the layer horizontal velocity, i.e. lowercase u and v (eq. 9.7 & eq. 9.8). I am a bit wondering how this set of equation can be coupled (see the snapshot below) since they use different velocities. There may be some tricks that I have not get yet. Can any one specify that?

Moreover, the continuity equation (eq. 9.3) is expressed in terms of depth-averaged velocity. However, the vertical velocity in the sigma-coordinate system is computed from the eq. 9.9 which is again a continuity equation but uses layer horizontal velocity. Can anyone specify how Delft3D-FLOW do when performing 2D and 3D modelling ?

Thanks in advance!