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

wavecon wave spreading and water level

Fajar Khaedir, modified 5 Years ago.

wavecon wave spreading and water level

Youngling Posts: 8 Join Date: 4/7/14 Recent Posts
Dear all,

I'm modelling flow simulation and coupling with online wave. On the flow module I use Time-series water level at the ocean boundary and I use wavecon file on the wave module. My questions are:
1. In the wavecon file, should I put same water level condition as in the bct file? or just put the water level to 0?
2. For the wave spreading, is there any way to use degree value instead of power? because my data is in degree. Or should I convert it to power manually? I have tried to change directional spreading to degrees in the "edit spectral space" option, but delft3d changed it to power ("Warning : choice for degrees modified into power"), and if I compare between I choose degree or power on "edit spectral space" option the result is not different at all in wavm file.
3. If I have to use power value for directional spreading, can I linearly interpolate from degree to power by using the table at page 186 in Delft3D-Wave Manual?

I'm sorry for my bad english, I hope you can understand. Thank you in advance for all your response.

Ruairi MacIver, modified 5 Years ago.

RE: wavecon wave spreading and water level (Answer)

Padawan Posts: 45 Join Date: 5/1/13 Recent Posts
Hi Fajar,

Re 1), With online coupling there is a part of the GUI (DATA group, Hydrodynamics tab) where you select how parameters from the FLOW model (water level, flow velocity, bathymetry, wind) are to be used.

Re 2), this has been a known issue for quite some time for both wavecon and TPAR approach for specifying wave boundary conditions.

When using the wavecon approach, the directional spreading value stated in the wavecon file is interpreted as a power (an ‘s’ value) regardless of what is selected in the GUI [or specified in the boundary section of the MDW file]. So far as I can tell the value is not converted in any way.

When using the TPAR approach, the boundary condition parameters contained in a TPAR file are read and the written to the SWAN input file as if the period and directional spread values represent a peak period and a cosine power. Again no conversion takes place. Furthermore the spectral shape is presumed to be JONSWAP with a peak enhancement factor value of 3.3.

Have a look at this thread.

Re 3), The approach described is a reasonable ‘first order’ way of converting between the power and st .dev. (degrees) representation of directional spread.