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! 


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: 

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





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


Message Boards

D3D Wave

Ed Atkin, modified 8 Years ago.

D3D Wave

Padawan Posts: 27 Join Date: 3/27/12 Recent Posts
Dear all,

I have 4 spherical system grids. Nesting outside on a grid with 0.0083 degree resolution, which his around 700 m.
The spacing on the next grid down is 0.0005, around 40 m
Grid down form that is 0.0002
And the last grid, is 0.00005 degrees, which is approximatly 5m.

The nesting works well down to the 3rd grid. However, the last grid has a nonsense output, with a small amount of wave data on the eastern boundary?

But, if I make the grid resolution twice the size, then the results are as expected. Although not very useful for its purpose due to the poor resolution.

See the image attahced. 5m is on left. 10 m on right.

So does anybody no of any reason why this would be happening?


Qinghua Ye, modified 8 Years ago.

RE: D3D Wave

Jedi Council Member Posts: 610 Join Date: 3/2/11 Recent Posts
Hi Ed,

Maybe your model touched the precision limitation of swan. As you know, swan is using single precision.
Would you like to try to use Cartesian coordinate system instead of spherical one to do your simulation? That might help you to avoid this kind of problem.