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

Bed composition file has no effect

Menno Eelkema, modified 8 Years ago.

Bed composition file has no effect

Youngling Posts: 1 Join Date: 10/17/11 Recent Posts
I'm tryin to run a Delft3D model with a simple vertically layered bed composition for an estuary. The schematization is very simple: one part of the estuary has three layers:
- a sandy top layer 0.5 meters thick
- below that a clay layer 3 meters thick
- below that nothing but sand again.
The rest of the estuary is sandy non-cohesive.

I've classified two sediment fractions in the sed-file (one sandy non-cohesive, one cohesive). In the mor-file, I've given the following input for the underlayer-input:

IUnderLyr = 2
MxNULyr = 3
TTLForm = 1
ThTrLyr = 2.0000000e-001 [m]
ThUnLyr = 5.0000000e+100 [m]
IniComp = bedcomposition.inb

In the bedcomposition file I've identified the three layers:

Type = mass fraction
Thick = layer1.thk
Fraction1 = 1.0
Fraction2 = 0.0
Type = mass fraction
Thick = layer2.thk
Fraction1 = 0.0
Fraction2 = 1.0
Type = mass fraction
Thick = layer3.thk
Fraction1 = 1.0
Fraction2 = 0.0

The .thk files are maps specifying the area with the hard layer within the estuary .

Still, when I run this, I do not see these layers in the output. What I do see are the values for the IniSedThick specified in the sed-file. These values are supposed to be overruled by the Inicomp-file. So what is missing here?