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

ylwrap problem at Debian 32bit with ifort12

Marcin Kawka, modified 9 Years ago.

ylwrap problem at Debian 32bit with ifort12

I've installed 32bit Debian with intel fortran 12 and mpich2 made from sources.
Unfortunately I get the following error while making in tools_gpl/vs/packages/vs/

/bin/bash ../../../../../config/ylwrap vs_l.l .c vs_l.c -- : -L
make[5]: *** [vs_l.c] B??d 1
make[5]: Opuszczenie katalogu `/home/marcin/delft/current_july/tools_gpl/vs/packages/vs/src'

Anyone got an idea how to solve it?
Adri Mourits, modified 9 Years ago.

RE: ylwrap problem at Debian 32bit with ifort12 (Answer)

Yoda Posts: 1221 Join Date: 1/3/11 Recent Posts
Hi Marcin,

It seems that Lex and Yacc are not installed. See
You need this to be able to build the small tool called vs. I expect you will not need vs, so you can also remove it from your local build environment.