1. Consulting Engr., Frankfurt (Kelkheim), West Germany; formerly, Research Engr., Inst. of Hydromechanics, Univ. of Karlsruhe, Karlsruhe, West Germany, Germany
2. Dir., Inst. of Hydraulic Research, The Univ. of Iowa, Iowa City, Iowa; during part of this study, Visiting Prof., Inst. of Hydromechanics, Univ. of Karlsruhe, Karlsruhe, West Germany, Germany