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

Problems with creation of .cco and .lga files

Maria C, modified 1 Year ago.

Problems with creation of .cco and .lga files

Youngling Posts: 3 Join Date: 4/11/18 Recent Posts

Dear all,


I am trying to run several models of a lake with Z-layers. The hydrodynamic model with FLOW works properly but the problem comes when I create the com- files to run some WAQ models. Although I am able to viasualize correctly the model domain in the GUI, the .cco and .lga files seem to be not correct, since when I go to QUICKPLOT and plot them I obtain just a line.

I have tried making the coupling via the built-in option in FLOW as well as with the COUPLING tool in the WAQ menu. The result is the same.

I attach the image of the lake domain as well as the .cco and .lga files.

I would be very grateful if you could give me some advice.

Best regards,



Sung Tae LEE, modified 1 Year ago.

Sharing my same Error (RE: Problems with creation of .cco and .lga files)



By keyword "lga", I found your posting and many others.


And yours is very similar with my case.


I just would like to share my case.


Plz refer to my posting. (

Chao Li, modified 1 Year ago.

RE: Problems with creation of .cco and .lga files

Youngling Posts: 5 Join Date: 6/16/19 Recent Posts
Hi,I think I have the same issue as yours, have you found a solution to this problem yet?