How comes that someone who is working at the former Computing Centre of a Technical University is going to collaborate with an astronomer? Well, that's bit of a strange story indeed!
I have decided to distribute the computer programs and accompanying documentation, with exception of the "coeffs" suroutine (containing all of the Physics and developed by Horst Fichtner himself), as public domain source code. It might serve as a (somewhat obsoleted) blueprint for describing anisotropic Convection & Diffusion within a hemisphere. The mathematics of Convection & Diffusion should better be replaced by a proper translation from my newer Delphi Pascal version. Also available are LaTeX sources of the accompanying PDF document, with a somewhat obsolete description of Convection. [ Note. Modern insights are worded here but they are not implemented (yet) in the ZONWIND code. ] Anyway, here are some visualizations of results obtained by Horst Fichtner.
I was in the opportunity to present a lecture about the numerics of the matter at the "Woudschoten 1996 conference" on September 26th, Thursday, 12.15 - 12.45, Zeist (the Netherlands). Title of the presentation: "On solving a Cosmic Ray equation". A (necessarely incomplete: partly hand-written) collection of accompanying overhead sheets was processed for inclusion in this Homepage.
I've been successful in porting a full blown version of the 3-D ZONWIND code to PC's, using (Turbo Pascal and) Delphi.