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

Flow model error when include sediment

Yuwana Sriraharjo, modified 2 Years ago.

Flow model error when include sediment

Youngling Posts: 2 Join Date: 7/29/16 Recent Posts
I have problem every time I run sedimentation in flow and wave model,

My research is to identify sedimentation and erosion in coastal area. Before I add sedimentation in my flow and wave model,and everything goes well.
After I add sediment and morphology area it always exited abnormally because water level change too high > 25.00 m

Here the note that I got from diagnosis file.
"ERROR Water level change too high > 25.00 m (per 0.5 DT) after 343 timesteps"...

Boundary that I used in flow model is water level and rieman with harmonic component.

Can anybody help me for this problem?
Alejandro Paladio, modified 2 Years ago.

RE: Flow model error when include sediment

Youngling Posts: 9 Join Date: 11/14/12 Recent Posts
Hey Yuwana Sriraharjo,

If the problem is only when you run the MOR-module of delft3D, you can try with:
SgrThr = 99.0
In the "Additional parameters" in the FLOW-Module.

There are some other options you can check:
For example, the Courant number, to see if the selected time step is the good one (in QUICKIN), or you need to make your time step smaller.
If that is correct, you can change in the "Physical parameters" tab, and then "Roughness", I use Manning around 0.02~0.04... or you can make it bigger... with that, the velocity will go down.

If you want, you can upload your model, I can help you,

Greetings from Mexico!