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

"Error - FlowFM: Roughness contains unspecified points, the calculation..."

Francisco Taveira Pinto, modified 5 Months ago.

"Error - FlowFM: Roughness contains unspecified points, the calculation..."

Youngling Posts: 3 Join Date: 1/29/20 Recent Posts
I am an user of Delft3D Flexible Mesh and I need to build a refined grid in order to draw five detached breakwaters. My question is how refined can my grid be in order to avoid this error, "FlowFM: Roughness contains unspecific points, the calculation kermel will replace these with default values". I already saw some possible solutions to solve this problem. Therefore, I merged circumferences but it made my grid less refined... I will show you my case study so that you can understand what I mean.This is the error:
This is my case study, located in Oporto, Portugal.image.png
These are detached breakwaters under study. My main goal is to study the morphodynamics.image.png
As you can see on the following image, the grid zone where breakwaters are going to be implemented is too refined. I am afraid that FM does not support this high resolution.image.png
I would like to know what can I do to make this study well and solve the problems I mentioned above.Thank you very much.
Best regards,
Francisco Taveira Pinto (Faculty of Engineering of University of Porto)