Willy's interest and excellence in computational astrophysics became already visible at this early stage of his career. Instead of using an available particle-in-cell code, provided by Gerhard Hensler, he developed his own, new grid code with refined mesh resolution at the boundary layer between the accretion disk and the central star. This provided much better spatial resolution and more accurate handling of the complex accretion flow. The results of his diploma thesis, his first papers, appeared in 1987 in the journal Astronomy & Astrophysics. This work also led to a research project, funded by the German Science Foundation, where Willy advanced his code to radiation-hydrodynamics.