[1] Faculty of Mechanical Engineering, Technion, Israel Institute of Technology, Haifa 32000, Israel
[2] Lehrst. F. Strömungsmechanik, University of Erlangen-Nürnberg, Cauerstraße 4, D-91058 Erlangen, Germany
[3] Fg. Stromungslehre und Aerodynamik, Technical University of Darmstadt, Petersenstraße 30, D-64287 Darmstadt, Germany