1. Research Engineer, Institute for Hydromechanics, Univ. of Karlsruhe, D-76128 Karlsruhe, Germany.
2. Research Associate, Institute for Technical Chemistry and Polymer Chemistry, Univ. of Karlsruhe, D-76128 Karlsruhe, Germany. E-mail: froehlich@ict.uni-karlsruhe.de
3. Professor, Institute for Hydromechanics, Univ. of Karlsruhe, D-76128 Karlsruhe, Germany. E-mail: rodi@uka.de