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

Steep slope from deep water to coastline

Hanieh Mohamadi Moghadam, modified 3 Years ago.

Steep slope from deep water to coastline

Youngling Posts: 4 Join Date: 8/20/17 Recent Posts
Dear Delft3D users,

I want to model hydro+wave with a slope of 27 percent from deep water to the coastline. I use Domain Decomposition technique with an 300mX500m rectangular domain and 2mx2m grid size as outside domain and an 98mX200m rectangular domain and 0.5x0.5m grid size as inside domain. With this spatial resolution, I tried different time step ranging from 0.2 min to 0.02min, however I keep receiving "Water level change too high" error. I assume there must be something wrong with the courrant number, but I don't know how to fix it.
I know the slope is very steep and I was wondering if anybody has similar problem.
The boundary con. is Water Level for the offshore side and Neumann for the lateral sides and nothing (open boundary) for the coastline.
I really appreciate if you give me your advice on how to fix this error.