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

about Neumann Boundary

Wendy Ni, modified 9 Years ago.

about Neumann Boundary

Youngling Posts: 3 Join Date: 12/20/11 Recent Posts

Recently, I have simulated the hydrodynamics condition in tidal flat with Delft3d. The model has three boundaries and I set the two cross-shore boundaries as Neumann Boundary.
But the FLOW result shows an unusually high velocity about 2-3m/s in boundary corner and sea water has tendency to get together in the middle to the sea.
I am wondering is there anyone else has met this problem and how should I set the Neumann Boundary with correct harmonic parameter such as amplitude or phrase?


chen ling, modified 8 Years ago.

RE: about Neumann Boundary

Youngling Posts: 14 Join Date: 1/2/12 Recent Posts
hi wendy,
do you have resolved the problems about Neumann boundary? recently i simulate the sediment transport in tidal condition, i want to set the open boundary as Neumann boundary, but i do not know how to set, could you give me some advice? And could you send an example with application of Neumann Boundary conditions?

Thanks and best regards
Chen ling