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

Workload of CPU with one and multiple processors

Diogo Mees Delfes Varela, modified 1 Year ago.

Workload of CPU with one and multiple processors

Youngling Posts: 1 Join Date: 9/12/19 Recent Posts
Dear all,
I am working with the reduction of input resolution for temperature (possible further inclusion of sediment) simulations [M N K = 160 55 10] and therefore the "performance timers" of the simulations are a very important parameter. Also, as I need to run several simulations, running them at the same time would improve my work.
In this regard, I would like to clarify some doubts that I have as computer sciences are not my area and I want to be sure that I am comparing in the correct way the "performance timers".
a) If I run more than one simulation at the same time without parallel computing, does Delft3D uses one processor for each simulation?
b) is this processor used exclusively for the simulation?

2) If I use parallel computing are the processors used exclusively for the simulation?
For this question I noticed that when I set 2 processors for a simulation, two of them work around 100% but the others also have an increase in workload.

I am using a 6 core processors PC so my idea was using 2 processors for simulation (running two simulations at the same time) and having another two for daily working (light programming). Of course, only if the processors were used exclusively for each simulation, I would be able to compare their timers, as the workload of one simulation would not influence the "performance timer" of another simulation.

I attach my batch file for the parallel computing in case is useful.

Thank you,