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

Bad results with curvilinear grid

Fernando Barreto, modified 7 Years ago.

Bad results with curvilinear grid

Padawan Posts: 74 Join Date: 6/21/12 Recent Posts
I'm trying to simulate an estuary with a curvilinear grid built in rgfgrid. I used as input astronomical components (the same problem occurs with time series). The problem is that when I put the color boundaries in Quickplot in the manual mode (and delimit it), I do not see the tide propagating along the estuary (what didn't happen when I used a rectangular mesh; I could see the tide propagating along the stuary); elevation values occupy entire grid instantly. That is, from time to time all the grid changes the color (does not spread the wave). I have tested various roughness and time steps. Anyone with experience with curvilinear grids could help me to solve this problem?

Adri Mourits, modified 7 Years ago.

RE: Bad results with curvilinear grid (Answer)

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

It does not sound like a problem related to switching from rectangular to curvilinear grid.

Boundaries are related to cells, denoted by indices (m,n). Are the dimensions of your two grids exactly the same?

When opening the model in the FLOW-GUI, some validation checks are performed. May be they help you further.


Fernando Barreto, modified 7 Years ago.

RE: Bad results with curvilinear grid

Padawan Posts: 74 Join Date: 6/21/12 Recent Posts
Thanks Adri for your reply.
I managed to solve the problem as follows: In the open boundary I put the splines straighter and closer together (more points on the boundary), and this solved my problem. I think I was putting too few points in the direction transverse to the boundary, which should be generating problem in numerical approximation.