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

Bijker formula

Guilherme Silva, modified 5 Years ago.

Bijker formula

Youngling Posts: 1 Join Date: 2/15/12 Recent Posts

I'm doing my PhD on sediment transport and I was checking the formulations on Delft3D manual. I have a question related to the formula 11.108 (page 359 of Flow Manual version 3.15 rev:18392).

This formula will define the coefficient for shallow or deep waters coefficient for Bijker formula. My questions is:

Following the b equation (11.108) it seems to be the other way around (BD should be BS and BS should be BD). I did some calculations and using the equation provided it leads to the opposite interpretation (5 for deep water and 2 for shallow water). I tried to change the BD for BS and seems to be ok (maybe a misswriting): smoothly changing from 2 (deep water) to 5 (shallow water). Am I right or I'm missing something?

Thank you in advance,