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

Nefis Error

Nophi Biton, modified 7 Years ago.

Nefis Error

Padawan Posts: 38 Join Date: 8/1/13 Recent Posts

I am trying to have a hydrodynamic simulation of coast, I have already established /created the .mdf file, but I get the error such as this:

Nefis error:
NEFIS message 5010:
Cel 'WIND ' already exists
While trying to define a cell for group WIND in file com-morong6.def

Nefis error:
NEFIS message 5014:
Group 'WIND ' already exists on file 'com-morong6.def'
While trying to define group WIND in file com-morong6.def

Nefis error:
NEFIS message 5019:
Data Group 'WIND ' already exists in data file 'com-morong6.dat'
While trying to create group WIND in WIND in file com-morong6.dat

what does this mean??
can anybody please me.
Adri Mourits, modified 7 Years ago.

RE: Nefis Error

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

It seems that you have modelled wind and try to write it to the com-file.

The easiest thing to try is removing the two files com-<runid>.def and com-<runid>.dat (unless you intend to use them as input) before starting an execution.

If that does not help: disable writing to the com-file (unless you intend to do so).

If that is not an option, you have to explain what you want to do: run Delft3D-FLOW with WAVE online, produce output for WAQ, how did you model wind?