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. 
 

** PLEASE TAG YOUR POST! **

 

 

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

 

 

Message Boards

Time series flow boundary condition

AM
Abdulla Mohamed, modified 5 Years ago.

Time series flow boundary condition

Youngling Posts: 16 Join Date: 6/12/13 Recent Posts
Hello.
I am relatively new to Delft3D.
I am trying to implement a time varying flow boundary condition at one of the model boundaries. I defined this boundary as a single line spanning the entire width of the upstream boundary.
I was wondering if I define a single time varying flow, how will the model split the flow across the boundary? Will the flow be equally divided across the length of the boundary?

Thanks for help.
Richard Measures, modified 5 Years ago.

RE: Time series flow boundary condition

Jedi Knight Posts: 178 Join Date: 3/23/11 Recent Posts
Hi,

What you are looking for is a "total discharge" boundary. This boundary distributes flow across the cells that make up the boundary. The way the flow is divided between the cells is well described in the user manual e.g. section 4.5.6 and section 9.4.1.2 (equation 9.81).

Cheers,

Richard
AM
Abdulla Mohamed, modified 5 Years ago.

RE: Time series flow boundary condition

Youngling Posts: 16 Join Date: 6/12/13 Recent Posts
Hi Richard,

Thank you for the information. It was very helpful.

Cheers,
Abdulla.
AM
Abdulla Mohamed, modified 5 Years ago.

RE: Time series flow boundary condition

Youngling Posts: 16 Join Date: 6/12/13 Recent Posts
Hi Richard,
Thanks very much for your replies to questions I posted on here. It was very helpful.
I had a few more questions I would be very grateful if you could give me your input on.

I wanted to just make sure if I am understanding how to implement flow directions correctly on the upstream boundary of a model I am working on.
I have attached a picture of the upstream boundary I am working with. Also I show the direction in which M and N are increasing.
So if I were to define a total discharge boundary conditions spanning the whole width of the upstream as shown, to specify flow in cubic meters/sec, I should have a sign convention for the flows as:
1. flows going into the model domain should be negative
2. flows going out of the model domain should be positive

Or do I have this wrong? Any input on this will be much appreciated.

Thanks a lot,
Abdulla.
Richard Measures, modified 5 Years ago.

RE: Time series flow boundary condition

Jedi Knight Posts: 178 Join Date: 3/23/11 Recent Posts
Hi Abdulla,

From your attached picture I'm pretty sure you have the sign convention correct. If you put a monitoring cross-section in the model at or near the boundary you should be able to check that the modelled flows are as desired - and you can always double check the flow direction by plotting velocity vectors in quickplot.

Cheers,

Richard
AM
Abdulla Mohamed, modified 5 Years ago.

RE: Time series flow boundary condition

Youngling Posts: 16 Join Date: 6/12/13 Recent Posts
Hi Richard,
Thanks very much for your comments.
I really appreciate all your input on this.

Cheers,
Abdulla.