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

Salinity modelling

Mostofa Sakib, modified 4 Years ago.

Salinity modelling

Youngling Posts: 2 Join Date: 9/18/16 Recent Posts
Hello everyone, I am quite a beginner in modelling. I have been running models for salinity in delft3d for last few weeks. I am facing problem regarding initial file. As i am running for salinity, i have to run the model 2 years setting the initial value of salinity for land equals to 0 and for sea 35. So, in case i want the output salinity for 2011 i have to run for 2010 with the initial values (as previously mentioned) and using those value of 2010 as base value model computes for my required year (in this case 2011). It takes almost 5 days for the total model to run. My query is how can i set a initial file from where the run will directly start for my required year so that the huge computing time gets minimized. I have heard about "hot start" for initial file in delft3d but don't know what it is. As i am facing quiet a trouble any sort of help will be highly appreciated. Thank you.
Adri Mourits, modified 4 Years ago.

RE: Salinity modelling (Answer)

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

Option 1:
If you have run your model for the year 2010, you can use the resulting map-files to restart your model for 2011. The GUI can help you to attach it. Please rename the map-files that you use to restart from to avoid overwriting data by the new simulation.
This option only works when your 2010 and your 2011 run are very much similar; if, for example, the grid is changed, this will not work.

Option 2:
Using the GUI, you can specify an "ini"-file containing initial conditions. You have to create this ini-file yourself, following the instructions in the manual, section "A.2.9 Initial conditions". This is a tedious, delicate job. If you plan to do this, first try to create an ini-file for a very simple small testcase before building one for your real model.

Option 3:
Using mpich to parallellize the computation will speed it up, thus reducing the 5 days of computation time.