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

Coupled D3D-FLOW/WAVE: Hot restarts

Ruairi MacIver, modified 5 Years ago.

Coupled D3D-FLOW/WAVE: Hot restarts

Padawan Posts: 45 Join Date: 5/1/13 Recent Posts
Is it possible to use the HOT-files to provide initial conditions for the D3D-WAVE model when restarting a (on-line) coupled FLOW-WAVE simulation?

I am aware a D3D-FLOW model can be HOT restarted using the "tri-rst" files or other map files. This is well documented in the manual and there are several posts on the forum describing this. However I can't work out how to force the first execution of the D3D-WAVE model in a restart to use a HOT-file for initial conditions.

The SWAN input file for the first execution doesn't include the command line "INIT HOTS 'hot...'" although executions at subsequent timestamps do.

Any ideas?

James Knighton, modified 4 Years ago.

RE: Coupled D3D-FLOW/WAVE: Hot restarts

Youngling Posts: 12 Join Date: 8/9/13 Recent Posts
I too am having this issue. I have a very long coupled FLOW and WAVE simulation for which I would like to supply initial water depth, velocity, and the wave field. I have tried a number of ways to get WAVE to read in a HOT start file, but it doesn't seem to want to take the file as initial conditions. The FLOW restart file however seems to work for initial conditions.
Qinghua Ye, modified 4 Years ago.

RE: Coupled D3D-FLOW/WAVE: Hot restarts

Jedi Council Member Posts: 612 Join Date: 3/2/11 Recent Posts
Hi Ruairi and James,

It has been a while. Is there any progress about this question? I may not know the exact reason by now either, just some thoughts below.

Is this possibly a SWAN problem or a WAVE problem? There is a known issue that SWAN (structured grid version, swan_4072ABCDE_del_w32_i11_omp) will get some problems when running in multithread/MPI mode.


Kit Stokes, modified 2 Years ago.

RE: Coupled D3D-FLOW/WAVE: Hot restarts

Youngling Posts: 9 Join Date: 11/8/16 Recent Posts
Hi all,

did you ever solve this problem? I'm trying to do the same thing (restart flow and wave from a point mid way through a previous simulation) and I can restart flow using a restart file, but there doesn't seem to be a way to restart the wave side.

As the hot start files that the wave side generates seem to get deleted as the simulation progresses, I wrote some matlab code to copy the files when they appear, so I have the hot start files I need for the subsequent simulation, but just no way to initiate with them. Could the solution be to give the 'INITIAL HOTSTART' swan command to delft3D somehow? Is there a way to give swan commands like this to delft3d in the mdw file in some way?


Kit Stokes