intro story D-Flow FM

 

D-Flow Flexible Mesh

D-Flow Flexible Mesh (D-Flow FM) is the new software engine for hydrodynamical simulations on unstructured grids in 1D-2D-3D. Together with the familiar curvilinear meshes from Delft3D 4, the unstructured grid can consist of triangles, pentagons (etc.) and 1D channel networks, all in one single mesh. It combines proven technology from the hydrodynamic engines of Delft3D 4 and SOBEK 2 and adds flexible administration, resulting in:

  • Easier 1D-2D-3D model coupling, intuitive setup of boundary conditions and meteorological forcings (amongst others).
  • More flexible 2D gridding in delta regions, river junctions, harbours, intertidal flats and more.
  • High performance by smart use of multicore architectures, and grid computing clusters.
An overview of the current developments can be found here.
 
The D-Flow FM - team would be delighted if you would participate in discussions on the generation of meshes, the specification of boundary conditions, the running of computations, and all kinds of other relevant topics. Feel free to share your smart questions and/or brilliant solutions! 

 

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We have launched a new website (still under construction so expect continuous improvements) and a new forum dedicated to Delft3D Flexible Mesh.

Please follow this link to the new forum: 
/web/delft3dfm/forum

Post your questions, issues, suggestions, difficulties related to our Delft3D Flexible Mesh Suite on the new forum.

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** PLEASE TAG YOUR POST! **

 

 

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

 


Message Boards

Boundary conditions - currents

Alessandro Lotti, modified 4 Years ago.

Boundary conditions - currents

Youngling Posts: 4 Join Date: 10/11/12 Recent Posts
Hi everyone,
I'm building a hydrodynamics model using FLOW package. the domain is a rectangular grid, 3 km x 3 km with dx=25m. There isn't any coast line because the domain is located offshore. I'm implementing this model using currents data along the depth as boundary conditions, so it's a 3D model and 30 layers, and I want to set flow boundary along all boundaries (north, south, west and east). I've started some simulation but the domain dries it out. Then I have added water level boundary condition but I obtain overflow and hight flow velocitys before the simulation stops.
On the flow manual (p. 48) I can read: "you should avoid applying the same type of boundary condition at all boundaries.[...] i.e. the channel will eventually dry up or will overflow". I can't avoid setting flow boudary along all boundaries because I'll miss information about. How can I set current boundary conditions correctly? I also have salinity and temperature data.
P.s. It's a year simulation with 3 hours flow boundary time step.
Thank you very much.
Alessandro
Adri Mourits, modified 4 Years ago.

RE: Boundary conditions - currents

Yoda Posts: 1224 Join Date: 1/3/11 Recent Posts
Hi Alessandro,

I don't understand why you can't use Astronomic boundary conditions when your model is offshore.

Is a Riemann boundary condition an option for you?

Regards,

Adri
Alessandro Lotti, modified 4 Years ago.

RE: Boundary conditions - currents

Youngling Posts: 4 Join Date: 10/11/12 Recent Posts
Dear Adri,
thank you for your answer. I'll try to explain. I have current data, I'd like to set these current values along all boundaries (North South East and West) as you can see in the figure. So I have set ,along all boundaries, current type with time-series (forcing type) per layer specified (vertical profile). Only with these type of boundaries the domain dries it out and I think it's because of lack of water level boundary. So I have set on the east boundary, not along all east boundary but along a part of it, the water level condition (forcing type: time-series) insted of current data. BUT the result is a flow with very high velocity through that boundary segment. With Reimann is the same and I don't have astronomic data but time-series current and level only. Why does it happen? How can I do? If I set current data along three boundaries and the water level on the fourth it works without problems, but I'll miss current data input.
Thank you very much
Alessandro

Attachments:

Adri Mourits, modified 4 Years ago.

RE: Boundary conditions - currents

Yoda Posts: 1224 Join Date: 1/3/11 Recent Posts
Hi Alessandro,

Your problem seems to be similar to this problem. Do the remarks at that post help you?

Regards,

Adri
Alessandro Lotti, modified 4 Years ago.

RE: Boundary conditions - currents

Youngling Posts: 4 Join Date: 10/11/12 Recent Posts
Dear Adri,
your link was very usefull. I've solved the problem setting Riemann boundaries along two side (North and South).
Thank you very much.
Regars,
Alessandro
HT
HO THINH, modified 4 Years ago.

RE: Boundary conditions - currents

Youngling Posts: 1 Join Date: 3/10/15 Recent Posts
Dear Alessandro,

Could you please share a simple version of your model here so that I can try it out? That would be greatly helpful to me since I am new to the field. Thank you very much.

Best regards,
Thinh