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

The density of cohesive sediment in Delft3D

K Liu, modified 2 Years ago.

The density of cohesive sediment in Delft3D

Padawan Posts: 48 Join Date: 10/23/13 Recent Posts
Dear all,

I am looking at the formula for cohesive sediment (mud) transport in the FLOW manual. Just something come into my mind, and I’d like to ask you for some comments:

In the input file, the user needs to provide the “specific density” and “Reference density for hindered settling calculations”. I think the latter only affect the hindered settling velocity. Is it correct?

Second, I was wondering how the “specific density” was used in a sediment model. It does not appear in the governing equation if the convection-diffusion equation was solved for the concentration in kg/m3; it does not affect the erosion and deposition either as the erosion rate is in kg/m2/sec (mass per unit area per unit time) and the settling velocity is a user-specified constant.

Any hints are appreciated. Thank you in advance!