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

Problem to start a simulation with domain decomposition

Johanna Metge, modified 5 Years ago.

Problem to start a simulation with domain decomposition

Youngling Posts: 2 Join Date: 3/2/15 Recent Posts
Hello all,

i'm trying to run a model with five sub-domains with domain decomposition. After starting the simulation, I get this error:

Deltares, FLOW2D3D Version, Feb 9 2015, 10:17:51 entry Flow2D3D::Run

Part I - Initialisation Time Dep. Data module...
runid : seaN
Part II - Creating intermediate files...
Part III - Initialisation of the Execution module...
Part IV - Reading complete MD-file...
Part V - Initialisation & checking input...
Part VI - Initialisation & checking second part...
switch coordinates-2: ( 1, 7)
switch coordinates-2: ( 1, 7)
d_hydro ABORT: [Iterator]
1) Error during initialization of subdomains: check tri-diag files.
2) "seaN": Wrong coupling point at ( 8, 2) Kcs=0 KcsInside=0
d_hydro ABORT: [Iterator]
1) Error during initialization of subdomains: check tri-diag files.
2) "seaW": Wrong coupling point at ( 2, 2) Kcs=0 KcsInside=0

In the tri-diag files are only warnings and one error (*** ERROR At least 2 observation points must be defined when writing to history file) but I don't need history files, so I think that is not the problem.

Has anyone an idea to fix this and to run the simulation?

Adri Mourits, modified 5 Years ago.

RE: Problem to start a simulation with domain decomposition (Answer)

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

If you don't need history files, you must specify in the input (GUI, output tab) that the history file should not be generated.

Creating the connection between subdomains is rather sensitve. If you created/changed the ddbound file manually, please have it generated by RGFGRID.

In case that doesn't help: if there are dry/inactive cells along the coupling boundary, try to split it, such that all coupling boundaries are completely along active cells.