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

D-WAQ PART - Changing the number of threads

gustavo gomes, modified 4 Years ago.

D-WAQ PART - Changing the number of threads

Youngling Posts: 2 Join Date: 12/18/12 Recent Posts
I'm using the PART model in an oil spill project, running a large number of simulations (about 500) in serial mode for probabilistic results. Until now was using the version of 4:00:02 Delft3D and the PART used only one (1) thread. However, this version showns some instabilities to write files when the simulation ends, generating error and pausing the serial simulations. Therefore I installed the version of 4:01:00 Delft3D that corrected these bugs. However, by default, this latest version of D-WAQ PART uses all threads of processor and I wonder if you can change the number of threads for each simulation. Since I am simulating about 4-5 models in parallel and need to manage the number of threads to avoid calculation trouble.

Thanks for attention,
Arjen Markus, modified 4 Years ago.

RE: D-WAQ PART - Changing the number of threads (Answer)

Jedi Knight Posts: 223 Join Date: 1/26/11 Recent Posts
You can control the number of threads by setting the environment variable OMP_NUM_THREADS to the required number. See for instance:

If you are using WIndows, then:

c:\> set OMP_NUM_THREADS=1
c:\> delpar

should do the trick.
gustavo gomes, modified 4 Years ago.

RE: D-WAQ PART - Changing the number of threads

Youngling Posts: 2 Join Date: 12/18/12 Recent Posts
Thank you Arjen. It worked.