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

Coupling with DelWAQ problem

veli yumruktepe, modified 9 Years ago.

Coupling with DelWAQ problem

Padawan Posts: 42 Join Date: 2/7/12 Recent Posts
Hi all,

At the end, I managed to compile Delft3D on a 64bit linux machine. With the same scenario I used in my windows machines, I also ran in linux both single processor and parallel processor with MPI, in a single domain. Both of their results were pretty much similar.

However, when I asked the mdf file to create communication files for the coupling with DelWAQ, single processor run worked just fine as always, but in the parallel run, 2 seperate communication files were created (i did 2 processor run) and both of them did not work in coupling procedure in DelWAQ. Is there a way to combine those two and make them work or is there an another problem?

veli yumruktepe, modified 9 Years ago.

RE: Coupling with DelWAQ problem

Padawan Posts: 42 Join Date: 2/7/12 Recent Posts
Let me explain the problem a bit more.

I have a big domain in the Eastern Mediterranean, where running in a single processor requires too much time. Since there is a parallel processing option, I ran the model with MPI option. However I also want to couple the FLOW results with the ECOLOGY compartment of the commercial product of Delft3D. In single processor run, coupling can be done without any problem, but when I set as an option to couple the parallel model with these lines in mdf file:

Flwq = some integers
ilAggr = some integers

the coupling is done, but with just ONE PART of the domain, for instance one of the grids that MPI divided, therefore I cannot get my whole domain coupled.

My first question is: Is there a way to get the whole domain coupled in MPI runs?

My second question is: How do you tell the MPI where to divide the domain, I also have some experience in ROMS, and there you can specify the subdomains in your grid when using MPI. The reason why I am asking this is that, if such an option exists, I can get by this way a portion of my domain coupled, area of most interest at least.
Adri Mourits, modified 9 Years ago.

RE: Coupling with DelWAQ problem

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

Not all functionality works yet in combination with parallel processing. Online running with WAVE and producing WAQ input files are two of them. It's on our "TO DO" list. In case you have a specific simulation time for which you want to produce WAQ input, you can run parallel, producing a map-file just before this time point and use that to restart in sequential mode, producing WAQ input for the specific time point.

Also controlling the splitting process is on our "TO DO" list. An option for this is to change the source code yourself and implement a hard coded split version dedicated to your model and your hardware. If you want to try this, I can guide you to the source code to be changed.