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

visualization of constituents

MC
Michelle Cardenas, modified 9 Years ago.

visualization of constituents

Youngling Posts: 4 Join Date: 10/31/11 Recent Posts
Hi,

I am adding a pollutant to the simulation. When plotting this constituent, the legend on the figure does not have a units label. How do I figure out the units. I have specified the flow and the density in the simulation.

Thanks,
Michelle
Bert Jagers, modified 9 Years ago.

RE: visualization of constituents

Jedi Knight Posts: 201 Join Date: 12/22/10 Recent Posts
Hi Michelle,

The unit of plotted concentrations matches the unit of the input concentrations of the constituents (pollutants/tracers). Since the FLOW GUI asks for kg/m3 that is also the unit of the concentrations when you plot the results.

More detail: for the equations that Delft3D solves for constituents/tracers the exact unit doesn't matter; the concentrations could be given in kg/m3, mg/m3, mol/m3, or something else per m3 and everything would work the same. The units of the constituents are not written to the output file and when implementing QuickPlot I didn't want to assume anything about the intended concentration unit. However, I now realize that the FLOW GUI specifically asks for kg/m3, and thus we could plot that unit.

Bert
MC
Michelle Cardenas, modified 9 Years ago.

RE: visualization of constituents

Youngling Posts: 4 Join Date: 10/31/11 Recent Posts
Hi Bert,

Great. Thanks for your help!
Michelle
MC
Michelle Cardenas, modified 9 Years ago.

RE: visualization of constituents

Youngling Posts: 4 Join Date: 10/31/11 Recent Posts
Hi Bert,

Could you comment on getting small negative values in some of the layers? The source has a concentration of e^-6 and then a few layers up the concentration is on the order of e^-12. At this layer we start to see negative numbers, which I was not expecting.

Thanks,
Michelle
Adri Mourits, modified 9 Years ago.

RE: visualization of constituents

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

See section 10.6.4 in the manual.
The default Cyclic scheme is robust and stable but does not guarantee to give positive solutions.
You have three options:
  • Accept that locally small negative concentrations may occur.
  • Switch to the Van Leer-2 scheme.
  • Use the Forester filter to smoothen the solution. Check your results carefully when using this. It may solve your problems, but it is also possible that it has some unwanted side effects on the concentration distribution.


Regards,

Adri
MC
Michelle Cardenas, modified 9 Years ago.

RE: visualization of constituents (Answer)

Youngling Posts: 4 Join Date: 10/31/11 Recent Posts
Hi Adri,

ok. Thank you for your help!
Michelle