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

Online-WAVE coupling

Erin King, modified 3 Years ago.

Online-WAVE coupling

Youngling Posts: 12 Join Date: 10/5/16 Recent Posts
I am new to Delft3D and am working my way through the tutorials. I am on the online WAVE coupling tutorial (6.4 in the WAVE user manual) and when I run the model I am getting the following error:

forrtl: The process cannot access the file because it is being used by another process.

forrtl: severe (28): CLOSE error, unit 796, file "Unknown"
Image PC Routine Line Source
wave.exe 0134AA14 Unknown Unknown Unknown
wave.exe 013344F4 Unknown Unknown Unknown
wave.exe 0129CE12 Unknown Unknown Unknown
wave.exe 01282B46 Unknown Unknown Unknown
wave.exe 0126FD4B Unknown Unknown Unknown
wave.exe 01253285 Unknown Unknown Unknown
wave.exe 012E09C4 Unknown Unknown Unknown
wave.exe 01252D04 Unknown Unknown Unknown
wave.exe 0138DA12 Unknown Unknown Unknown
wave.exe 0146F4A1 Unknown Unknown Unknown
kernel32.dll 7686336A Unknown Unknown Unknown
ntdll.dll 77499902 Unknown Unknown Unknown
ntdll.dll 774998D5 Unknown Unknown Unknown

I have done a bit of research to see that the error is “forrtl” = fortran run-time library (so it is a fortran error)
“severe (28): CLOSE error” = FOR$IOS_CLOERR. An error condition was detected by the Intel Fortran RTL I/O system during execution of a CLOSE statement.

Some forums suggested it was down to local write permissions but that did not seem to help when I ensured I had full permissions on the drive.

Any help would be vastly appreciated.

Erin King, modified 3 Years ago.

RE: Online-WAVE coupling

Youngling Posts: 12 Join Date: 10/5/16 Recent Posts

This error was tracked down to Kaspersky Antivirus. The "System Watcher" component was interfering with the communication/ stopping the model.

Disabling the component fixed the issue.