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

Group Velocity Calculation for Multiple Wave Components

Hans K, modified 2 Years ago.

Group Velocity Calculation for Multiple Wave Components

Youngling Posts: 1 Join Date: 12/22/17 Recent Posts
Hi All,

I am a beginning coastal modeler and I haven't been able to find a general equation for wave group velocity, when more than two components are involved.

It seems that all the equations for group velocity I could find fall into one of the two approaches:

1. By taking the derivative of wave frequency with respect to wave number: i.e., del(omega)/del(k)

2. By multiplying the phase velocity C by a ratio n.

Both approaches, however, assume that the wave group consists of only two individual waves with very similar wave periods.

Is there any general equation available that can be used for any arbitrary number of waves with widely different periods?

Any help will be greatly appreciated. My apologies if this is such a basic question, but it has been bothering me to a great degree..