1. Department of Aeronautics and Astronautics; Stanford University; Stanford California 94305 U.S.A.
2. Department of Mechanical Engineering; Stanford University; Stanford California 94305 U.S.A.
3. Institute of Computational and Mathematical Engineering; Stanford University; Stanford CA 94305 U.S.A.
4. Institute for Applied Analysis and Numerical Simulation; University of Stuttgart; Pfaffenwaldring 57 Stuttgart 70569 Germany