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

Wave boundary condition - point source

Samantha Maticka, modified 10 Days ago.

Wave boundary condition - point source

Youngling Posts: 4 Join Date: 10/2/20 Recent Posts

I am trying to run Delft3D with just waves. I am using a curvilinear grid and would like to force it with time-varying waves that approach from the southwest. Can anyone advise on the best wave to do this? What I have tried is resulting in a point-source effect of waves rather than a spatially uniform forcing. I included pictures below.

I have field observations from a single location that I would like to force my model with. It is about 20km from my area of interest. Currently, I am using a curvilinear circular domain, and I am applying a non-stationary time-varying boundary forcing by using a TPAR file, specifying a 'segment' type of boundary in the [Boundary] block of the .mdw file, and declaring specific times to perform the calculations as [TimePoint] blocks. Something like this:

   Time                 =  0.000000000000000000e+000             
   WaterLevel           =  1.000000000000000000e+000         
   XVeloc               =  0.000000000000000000e+000         
   YVeloc               =  0.000000000000000000e+000         
   WindSpeed            =  0.000000000000000000e+000         
   WindDir              =  0.000000000000000000e+000  
   Time                 =  60.0      
   WaterLevel           =  1.000000000000000000e+000         
   XVeloc               =  0.000000000000000000e+000         
   YVeloc               =  0.000000000000000000e+000         
   WindSpeed            =  0.000000000000000000e+000         
   WindDir              =  0.000000000000000000e+000  
   Name                 = PointP6                  
   Definition           = xy-coordinates
   StartCoordX          = 575571.0
   EndCoordX            = 575571.0
   StartCoordY          = 8177208.0
   EndCoordY            = 8177208.0 
   SpectrumSpec         = from file        
   Spectrum             = spectral.bnd

I tried using a 15-point segment for the boundary (~1/15th of the perimeter), but the accuracy reported in the PRINT file from SWAN suggested that the model did not converge. So I reduced it from 15 points along the encompassing boundary to 2 points. It looked to converge, but both results had somewhat of a 'beam-like' behavior.

Any suggestions would be greatly appreciated!!

Thank you emoticon
This is what our results look like. For a depth like this (outside the red circle is not part of the domain):
The significant wave height looks like this (1st is 15-point boundary, 2nd is 2-pt):


but this is what we would like them to look like: