Frequently Asked Questions

What do I need to work with the dolfyn CFD code?

Just a few things:

  • A Fortran95 (f95) and a Fortran77 (f77) compiler.
    Most f95 compilers compile also f77 code. Using compilers of different suppliers will normally not work (e.g. g77 for Fortran77 and ifc for Fortran95).
    Please have a look at the work on g95 at
  • A program to make grids or meshes (a ‘mesher’). For example CGX or commercial preporocessors like Femap.
  • A program to visualise the results (a ‘postprocessor’). For example OpenDX, ParaView, GMV or VisIt.

What is a Makefile?

A makefile is used for the development of codes under Unix and Linux. After a change of the source code, a new executable is obtained after issuing the command ‘make dolfyn’. Please check the names of the compilers in the makefile.

Fortran? But isn’t that hopelessly old fashioned?

Lots of people who have not encountered the latest Fortran compilers react in this way. Fortran 77 is indeed a bit ‘old fashioned’ and had some serious limitations. The language was developed way back in 1954 at IBM and has been updated since. Well known versions are Fortran IV (or Fortran 66), Fortran 77 (the well known standard), Fortran 90 and soon followed by Fortran 95. If number crunching is what you are up to then Fortran (95) still is the best horse for your course. Fortran 95 was replaced by Fortran 2003, and later by Fortran 2008. Dolfyn uses some Fortran 2008 syntax. With g95 and f03gl you can even do OpenGL!

Does dolfyn run on Windows?

Yes, why not? It is an open source CFD code. Compile the code and go ahead. Please have a look at this.

H’m, I do not fancy that compiling stuff. Are there any binaries I can download?

There are some binaries for SuSE GNU/Linux 9.0. here.

I want to use dolfyn at work. Is that allowed?

Yes, be our guest. The copyright and ownership of the code do not pass. If you would like to support our work (financially); please have a look at the next question.

Where do I find Pre and Post-Processors?

Some Post-processors:

And a Pre-processor:

I do not live in The Netherlands, may I still use dolfyn?

Yes, why not?