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

Validating WAVE model outputs to buoy

Charlotte Lyddon, modified 1 Year ago.

Validating WAVE model outputs to buoy

Youngling Posts: 7 Join Date: 10/19/15 Recent Posts


I am currently running online FLOW-WAVE simulations for a hypertidal estuary in 2D-horiztonal depth averaged mode. The model is forced from each end using tidal and river time series, space varying wave conditions along open sea boundary (using a .bcw file) and a space varying wind and pressure field. The model grid has been refined along the coastline for improved accuracy of wave height prediction. I am running simulations for 36 hours which covers a spring tide and a passing storm event. As an additional note, the model becomes unstable when triads and diffraction turned on in WAVE and exits, so my wave simulations do not include this. 

The tidal time series from FLOW validates well to 4 tide gauges along coastline. However I am currently having issues validating modelled significant wave height to 4 wave buoys in the estuary (the locations of which are shown in the attached image in the grid). As shown in the attached image, there is significant tidal modulation not present in the wave buoys. The magnitude of Hs at times seems correct, but the overall time series is not well matched.

Is it possible to limit tidal modulation in model, or are there any settings I might be missing which could help? I have tried changing Manning friction, JONSWAP friction, running WAVE without extending wind and water level from FLOW, but none of these make that much of a difference. I understand that bathymetry is hugely important, and the fact this is an estuary with a tidal range exceeding 10 m makes things complicated.

I'm just looking for some advice as what I could do next to improve the accuracy of my wave simulations in the estuary, or if I need any additional forcing data to help! Maybe someone here has had a similar issue and is able to offer some advice!

Best wishes