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

Multi Thread Efficiency

Christopher Esposito, modified 7 Years ago.

Multi Thread Efficiency

Padawan Posts: 35 Join Date: 10/16/12 Recent Posts
Hi all,

When I run my simulations in parallel (on windows7x64), I often run into a situation where one thread seems to be limiting the rest. In the current case (see attachecd image) I am running with six threads. One thread is at 12% (approximately a full core) but the other five are at near 5%.

I had thought that FLOW tried to distribute the active cells equally, but that doesn't seem to be happening here. Is there anything that I can do so that I am using all six cores to capacity?

Adri Mourits, modified 7 Years ago.

RE: Multi Thread Efficiency

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

I'm afraid you have to change the source code. Here is a bit more info.