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

Wind implementation for SWAN

Scott Baker, modified 6 Years ago.

Wind implementation for SWAN

Youngling Posts: 4 Join Date: 10/23/13 Recent Posts
I would greatly appreciate anyone who can help me implement wind into my SWAN model.

I have an unstructured computational grid, and I'm trying to add wind using a regular grid that is slightly larger that the computational grid.
For now I setup a very simple regular grid with 9 nodes (3x3) to do some initial verifications. For these runs I have turned off any wave inputs, and I'm only looking at wind input.

Here’s the structure of my wind input file:
Overall header line
u1 u2 u3
u4 u5 u6
u7 u8 u9
v1 v2 v3
v4 v5 v6
v7 v8 v9

And the corresponding lines in the *.swn steering file:
INPGRID WIND REG longitude latitude -45 2 2 1.58 0.68
READINP WIND 1 'dummywindfile.wnd' 4 1 1 FREE

It appears that SWAN accepts the input file, however the results are unreliable. If the wind is set along a cardinal direction (purely N,E,S, or W) the model will only achieve ~20% accuracy after 50 iterations and the results are clearly garbage. If the wind is set along an arbitrary direction the model seems to provide reasonable results (wave growth along the direction of the wind).

For calculating the u,v-components, I’m using Cartesian notation (+U when wind blows eastward, +V when wind blows northward). My model is running in NAUTICAL mode, but I don’t think that matters in this instance.

Can anyone tell me what I'm doing wrong? Ideally I would like to incorporate spatially- and time-varying wind into my model.
Much appreciated!
Qinghua Ye, modified 6 Years ago.

RE: Wind implementation for SWAN

Jedi Council Member Posts: 612 Join Date: 3/2/11 Recent Posts
Hi Scott,

It seems to me a SWAN problem. I am not very clear about that.

Furthermore, can you try to impose the spatially- and time-varying wind, in the format of amp, amu and amv in Delft3D-WAVE? I think that is even easier to fulfil your purpose. As to the format of the files, refer to Delft3D-FLOW manual A2.8.2. Both Delft3D-FLOW and WAVE can use these types of files.