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

VolMin for Hydrodynamic coupling

Martin Schueder, modified 5 Years ago.

VolMin for Hydrodynamic coupling

Padawan Posts: 52 Join Date: 10/8/13 Recent Posts
Hello,

Just a quick question: when I am creating my hydrodynamic coupling file from a FLOW .com file, it fails to produce the .hyd file because of the error "Volume is less than VolMin ( =1 m3)"

Is there any way to decrease this value of VolMin or is it rigidly built into the program? I am modelling in 3 dimensions and am hoping to have a spatial discretization of less than 1 m3. My velocities are on the magnitude of 1.4 e^-7 m/s and my time step is about 1 second so the courant criterion would not be compromised to my knowledge.

Thank you!

Martin
Michel Jeuken, modified 5 Years ago.

RE: VolMin for Hydrodynamic coupling (Answer)

Jedi Knight Posts: 156 Join Date: 1/21/13 Recent Posts
Hi Martin,

The minimum value is not hard coded in the coupling program, but the GUI always writes the same setting. It is possible to interfere with it. After writing the input from the coupling program, you wil see that there is a settings file created named couplnef.inp. In it you will see a line saying:

1.0 *** volumes smaller than 1.0 are reported

There you can change it before you run the coupling.

However, if you do not change it, you should still have a hyd file, only the volumes are set to a minimum value of 1. Are you sure that you see an error, and not a warning?

Michel
Martin Schueder, modified 5 Years ago.

RE: VolMin for Hydrodynamic coupling

Padawan Posts: 52 Join Date: 10/8/13 Recent Posts
Hi Michel,

I think you are correct and that I misinterpreted the message in the coupling report. Just one last thing. You say:
"1.0 *** volumes smaller than 1.0 are reported

There you can change it before you run the coupling."

How should I go about changing it? Should I simply delete the line in the file?

Thank you!

Martin
Qinghua Ye, modified 5 Years ago.

RE: VolMin for Hydrodynamic coupling (Answer)

Jedi Council Member Posts: 612 Join Date: 3/2/11 Recent Posts
Hi Martin,

What Michel means is: change the line in hyd file manually from:
"1.0 *** volumes smaller than 1.0 are reported" to
"0.01 *** volumes smaller than 0.01 are reported".

But you have to keep in mind every time when you got a new hyd file. Don't forget.

Hope this solves your question.

Qinghua
Michel Jeuken, modified 4 Years ago.

RE: VolMin for Hydrodynamic coupling

Jedi Knight Posts: 156 Join Date: 1/21/13 Recent Posts
Hi,

A late new comment to add to this discussion that it is always better to use the direct coupling from FLOW to WAQ without the dedicated coupling program coup203 that we intent to stop in the future. This way no minimum value is applied. You can find it in the FLOW GUI on the Output screen as 'Export WAQ input', or 'Online coupling for WAQ' in older versions.

Michel
DH
Daniel Harrison, modified 3 Years ago.

RE: VolMin for Hydrodynamic coupling

Youngling Posts: 4 Join Date: 1/11/16 Recent Posts
Hi Michael,

I am running into this same problem trying to couple a DD FLOW simulation to PART.

Even if I edit the individual .inp files for each sub domain, they appear to be written over when I execute the coupling routine (from the GUI).

Is there any way to get around this???

Daniel