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

Problem: network is not orthogonal

Roger Wang, modified 4 Years ago.

Problem: network is not orthogonal

Youngling Posts: 8 Join Date: 10/12/15 Recent Posts

I have generated a grid from GMSH, and converted it to netCDF. When I started the model running in Delft3D FM, I received the following error message:

17:49:49.7754 The kernel reported the following error(s):
** ERROR : network is not orthogonal

(Errors extracted from logfile, located at: ...\Project1.dsproj_data\FlowFM_output\FlowFM.dia)

Could anyone help me out?

Adri Mourits, modified 4 Years ago.

RE: Problem: network is not orthogonal (Answer)

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

Delft3D FM is very strict on the grid being orthogonal. You can make it orthogonal using RGFGRID. RGFGRID is part of the Delft3D GUI. You can obtain it free of charge by filling the request form, linked via the "TEMPORARY EXTRA SERVICE" at the top of this page.

Please put FM related post on the page


Reza Shafiei, modified 3 Years ago.

RE: Problem: network is not orthogonal

Youngling Posts: 2 Join Date: 11/7/17 Recent Posts
Hi Adri,

I have the same issue and tried "orthogonalise grid" feature in RGFGRID. But, it hasn't resolved the issue.