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

error only in a smaller domain

mercy varghese, modified 7 Years ago.

error only in a smaller domain

Youngling Posts: 17 Join Date: 8/6/13 Recent Posts

I'm pretty much new to modelling. What I'm finding is the model execution stops abruptly in 3D FLOW with an error : water level exceeding 25 m when I use a domain very near to coast.
But when I use a larger domain far into the open ocean there is no error.
I'm using a spatially varying wind.
1.1km rectangular grids time step of 0.5min
Gebco 8 bathymetry.

all other parameters have their default value

Can anyone explain to me this......

Arnold van Rooijen, modified 7 Years ago.

RE: error only in a smaller domain (Answer)

Hi Mercy,

There may be various reasons why the model crashes. For example, it might have to do with sudden deep points in your bathymetry, or perhaps your boundary conditions vary too much or contain an error. Please, also check this discussion.

mercy varghese, modified 7 Years ago.

RE: error only in a smaller domain

Youngling Posts: 17 Join Date: 8/6/13 Recent Posts
Hi Arnold,

Earlier the grids I used were created using Dash Board. I created a domain with approximately 250m resolution near the coast using RGFGRID. The model seems to work perfectly then.
Do you why that may be? Also I will check into the bathymetry changes in the former grids.

emoticon I appreciate the fact that you have replied to my queries. thankyou.
Adri Mourits, modified 7 Years ago.

RE: error only in a smaller domain (Answer)

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

May be this discussion helps.

What happens with a smaller time step?

If you write (map-)output in the last steps before the crash, do you see strange things?