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

Theoretical questions

Pablo Muñoz, modified 5 Months ago.

Theoretical questions

Youngling Posts: 2 Join Date: 3/4/20 Recent Posts
Hi everyone! 
I have been a Delft3d user for two months and I have the following theoretical questions, related to each other, that are not clear to me reading the manuals:
1. What does voxel look like in 3D mesh? In particular, are the top and bottom faces of a cell leaning so that their vertices correspond to the vertices depths?  
2. To be clear about how to calculate flows, I wonder how are the cells adjacent to the bottom and edge in the sigma model? How is the cut-cell on the boundaries in the sigma-model? In the Z-model it is clear to me that they are represented as a staircase, but in the sigma-model not, since in theory it adapts to the background.  
3. How the (land-water) edge of the area to be modeled is defined? is it defined at the vertices or in the center of the corresponding cell?  
Thank you in advance,