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

Bottom roughness(manning) and viscosity/diffusity

Norlan Baga, modified 5 Years ago.

Bottom roughness(manning) and viscosity/diffusity

Youngling Posts: 10 Join Date: 1/18/14 Recent Posts
Good day!

I want to ask the effect of the bottom roughness and viscosity/diffusity during a simulation? I'm currently using DELFT3D on my undergraduate study about computational analysis of historical storm surge along Manila Bay (Philippines). Since I can't find any data about the bottom roughness of the bay, I'm only using uniform data (u and v) of the manning's equation. Before running all the historical typhoons that pass through the bay, I need to calibrate my model's physical parameters by running a series of simulations with varying constants(uniform) used to the said parameters then comparing the results to the reported storm surge height during a specific typhoon. I just thought that by understanding the effects of these constants to the model, I may come up with a better (realistic) model to be used on my study.

Thank you very much!


Norlan Baga
Qinghua Ye, modified 5 Years ago.

RE: Bottom roughness(manning) and viscosity/diffusity (Answer)

Jedi Council Member Posts: 612 Join Date: 3/2/11 Recent Posts
Hi Norlan,

You need calibration and/or sensitivity tests to determine the parameters of your model.