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

Non-stationary Delft3D issues

Julia Hopkins, modified 5 Years ago.

Non-stationary Delft3D issues

Youngling Posts: 14 Join Date: 1/1/13 Recent Posts

I am attempting to run a coupled WAVE-FLOW model with four nested grids in non-stationary mode (for the WAVE model). I have successfully run this coupled, nested set-up in stationary mode several times.

The model appears to be unable to complete a WAVE run in non-stationary mode, however. The common error is "Terminating error: Allocation problem: array AC1 and return code is 41" -- which I think means that the model believes my grids to be too large.

Is the interpretation of this error code correct? Is there a reason why my grid sizes, appropriate for stationary mode, might not work in non-stationary mode?

Thank you for your help!!


Adri Mourits, modified 5 Years ago.

RE: Non-stationary Delft3D issues (Answer)

Yoda Posts: 1224 Join Date: 1/3/11 Recent Posts
Hi Julia,

I assume that your error message appears in between the following two lines:
<<Run SWAN...
>>...End of SWAN run
In that case it is generated by SWAN and you have to address your question to the SWAN support team.