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

Iinternally limited max wind speed when using instationary D3D WAVE?

Ben Williams, modified 6 Years ago.

Iinternally limited max wind speed when using instationary D3D WAVE?

Jedi Knight Posts: 114 Join Date: 3/23/11 Recent Posts

I have come across something unusual during a test simulation.

I am running D3D WAVE for a region that is a semi-enclosed Gulf of water (70m depth, ~200km east-west by ~200km north-south). If I run using *stationary* assuming a wind speed of 35m/s then I get wave heights of up to 16m (and Tp ~ 18 seconds), which is what one would expect for an equilibrium situation for a body of water that size and wind speed of that magnitude.

However if I run using *in-stationary*, for a period of 24 hours, using dt=15 minutes and outputting maps every 60 minutes, then the wave height within the gulf is limited to a uniform value of about 2.5m. Tp never exceeds a uniform value of about 5.5 seconds.

This pattern is also repeated if I use spatially variable winds, such as MeteoFiles. The maximum wave height never exceeds ~2.5m and the maximum Tp never exceeds ~5.5 seconds. This is the case even when simulating cyclone processes for time when observed data suggests wave heights well in excess of 2.5m.

Is there perhaps some kind of internally limited value that has been set to guarantee numerical stability, by which D3D WAVE differs slightly from the standalone version of SWAN?



Version information:

- Delft3D-WAVE Version, May 27 2011, 14:26:44
- Open source