Haecheon Choi , Michael Hinzey & Karl Kunisch& Dept. of Mechanical Engng, Seoul National University, Seoul 151-742, Korea y Fachbereich Mathematik, MA 6-3, Technische Universit at Berlin 10623 Berlin, Germany & Institut f ur Mathematik, Universtitat Graz, A-8010 Graz, Austria Abstract In the present paper suboptimal boundary control strategies for the time-dependent, incompressible ow over t...