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

Riemann boundary condition for time series of tide

Reinaldo Barriga, modified 5 Years ago.

Riemann boundary condition for time series of tide

Youngling Posts: 7 Join Date: 10/21/13 Recent Posts
Hello everyone:

My name is Reinaldo, I'm working on a hydrodynamic model, for my open boundary condition I use Tide, which I obtained through a global model of tide When I tried using the condition of Riemann in Delft3D Flow, I noticed that I was asking the value in meters / second, after reading the manual I do not stay at all clear, however when performing harmonic analysis and modeling with the astronomical parameters succeeds in obtaining the value of m / s based on the time period of each constituent.

Can anyone help me understand how to use the Riemann boundary condition if I use a time series of tide (transform from meters of tide to meters/second of tide) ?.

thank you very much

Reinaldo B. Barriga
Danker Kolijn, modified 5 Years ago.

RE: Riemann boundary condition for time series of tide

Youngling Posts: 10 Join Date: 11/4/14 Recent Posts

The Delft 3D FLOW manual discusses Riemann boundaries on page 205-206.

I generate my Riemann boundaries in matlab using model inputs of both water level and current from a model such as HYCOM. this gives you:

R = U +/- (water level)*sqrt(g / depth)

where +/- is dependent on the U (velocity component) direction perpendicular to your boundary.
Hope that clears it up.