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

Modeling a confluence in a Meander

Guillermo Acuña Robles, modified 4 Years ago.

Modeling a confluence in a Meander

Youngling Posts: 2 Join Date: 8/20/14 Recent Posts
Good afternoon to everyone!
I'm trying to model a meander which receives input from another river. I have 3 boundary conditions entered as time series. 2 of the boundary conditions are associated income flow and the other I assigned water levels. When I run the model the flow direction does not match. One of the conditions where the flow should enter is behaving as an output condition.

I have already checked the bathymetry in the boundary conditions and have rotated the grid but the problem persists. Does anyone have any idea what might be happening and how could I fix it?

I appreciate any kind of collaboration
Adri Mourits, modified 4 Years ago.

RE: Modeling a confluence in a Meander (Answer)

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

According to the manual (section Discharge), a positive flow indicates a flow into the model.

Try to switch the sign to see what happens.

If this doesn't solve your problem, please zip the full set of input files and attach it to a post on this forum. Ideally the model is as much simplified as possible and still showing the problem.