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

Boundary conditions surrounding entire island?

Curtis Swanepoel, modified 3 Years ago.

Boundary conditions surrounding entire island?

Youngling Posts: 11 Join Date: 4/4/16 Recent Posts
Hi all

I am trying to make a model with of Mnemba Island in Zanzibar.

I have a 2km squared flow grid surrounding the island, a larger coarser grid surrounding the island and the entire reef and a very large coarse wave grid.
For the boundary conditions in the flow grid. What should these actually be if im including tidal variations. I have had them as North and South being Neumann with 0 gradient over the two week period. and West and East both being water level boundaries with the tide imposed into the bct file. Then in the wave I just use and the the flow grid water level so the second grid uses the tidal variations aswell .is this correct??

Thank you for your time