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

Questions regarding Water level change and Hs=0

Deepshikha Dalchand, modified 5 Years ago.

Questions regarding Water level change and Hs=0

Youngling Posts: 1 Join Date: 3/16/15 Recent Posts

I am a Master's student who is doing her thesis using Delft FLOW coupled with WAVE. I am quite new to the software so I apologize in advance for the newbie questions posed by me. emoticon

I have two questions for 2 different models I am attempting to make:
1. The thing is, I am trying to make a model for a bay area where there is also a discharge of a major river system. So, I have three boundaries, one of which is
water level type with astronomic forcing, another Reimann with astronomic forcing and the last one is total discharge with time-series. However, I keep
running into this error message:

No convergence in UZD at tstep: 3
*** WARNING No convergence in DIFU for resp. constituent nr. & tstep:
Water level change too high > 99.00 m (per 0.5 DT) after 7 timesteps in the following points:

I have tried remaking the grid multiple times, as well as decreasing the time step, but I always get this error message and then FLOW aborts. I tried checking
the bathymetry but the depth file was made from the interpolation of the bathymetric points through QuickIn, There are areas where there is a bit of a steep
rise in depth as it is the start of a submarine canyon, so I am not sure if this could be related to the problem?

2. I have another model, and for this Delft FLOW coupled with WAVE completes successfully. For both of the models I am using a Wavecon file, however for
this model, the Hs(m) computed=0 throughout. I have been unable to understand why this could be happening.

I would be extremely grateful if anybody could help me with these queries and point me in the right direction, please.

Thank you!
Warm regards,
Bay model