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

 

 

Message Boards

Instability - mean depth at cell centres

RM
Richard McSherry, modified 8 Years ago.

Instability - mean depth at cell centres

Youngling Posts: 2 Join Date: 2/5/13 Recent Posts
Hi,
I have noticed that there appears to be an instability when selecting the mean depth at cell centres, rather than the max depth of the four surrounding grid points. I am using a Z scheme, trying to model 3D temperature profiles in a lake - the temperature variation becomes unstable when the water level moves up and down. Has anyone else found this?
The documentation does suggest that using mean depth could have some issues associated with it. I have found that using max depth gives a much better temperature computation, but this scheme isn't well suited to areas with steep bathymetry - the depth is always significantly over-estimated (reducing horizontal cell size is an option, but not practical for me due to prohibitive run times).
Thanks in advance for any advice.
Richard
Adri Mourits, modified 8 Years ago.

RE: Instability - mean depth at cell centres (Answer)

Yoda Posts: 1221 Join Date: 1/3/11 Recent Posts
Hi Richard,

Most important issue: Please switch to the recently tagged version 5.01.00.2163. This contains very thorough Z-model updates.

If that is not enough: Try adding the following two lines to the mdf-file (and remove other Trasol/Momsol lines):
Trasol= #iupw#
Momsol= #iupw#

This switches on some more implicit algorithms.

Regards,

Adri
RM
Richard McSherry, modified 8 Years ago.

RE: Instability - mean depth at cell centres

Youngling Posts: 2 Join Date: 2/5/13 Recent Posts
Hi Adri,
Thanks very much for the reply. I am presently trying to compile the new version and will test your suggestions.
Thanks again,
Richard