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

Delwaq2 NaN value for continuity-check

GS
Gholamreza Shiravani, modified 2 Years ago.

Delwaq2 NaN value for continuity-check

Padawan Posts: 65 Join Date: 6/25/16 Recent Posts

Hi,

After running Delwaq2, the continuity value becomes NaN in some part of Domain. Could you tell me the reason of that? When the Delwaq2-parameters beom NaN (None a Number)?

MJ
Michelle Jeuken, modified 2 Years ago.

RE: Delwaq2 NaN value for continuity-check

Jedi Knight Posts: 154 Join Date: 1/21/13 Recent Posts

Hi,

 

This could not be due to any process parameter, since no processes are involved. It could happen when you have used a transport scheme that is not appropriate for the case you are modelling and/or when your time step is too big. Try using an other scheme and/or a smaller time step. High vertical dispersion could also cause problems. You could apply a factor on the vertical dispersion from FLOW.

 

Michelle

GS
Gholamreza Shiravani, modified 2 Years ago.

RE: Delwaq2 NaN value for continuity-check

Padawan Posts: 65 Join Date: 6/25/16 Recent Posts

Hi Michelle,

Time-step and numerical methods are not the reasons, because I tried implicit methods (such as 15 or 16) as well as explicit methods (e.g. 11) with different small time-steps (like 5 seconds!) but the NaN problem is still printed in .mon-file. 

Using the .ada-file in a map-view, I realized that  NaN values are started from the dry and wet areas (the tidal part of the Domain(e.g. an island)) and expanded to rest parts of the domain till all cells become NaN. Has Delwaq a problem with dry/wet boundaries? I have in my open-boundary an island, where is included in my D-Flow and using bathymetry elevations behaves on its boundaries as dry/wet boundaries. But in Delwaq, these areas become NaN and cause to all cells after some time-steps become gradually NaN. Could you tell me how can I solve this problem?