1. Marine Renewable Energy Laboratory; Vortex Hydro Energy, MRELab, University of Michigan, Ann Arbor, MI 48109 e-mail:
2. Marine Renewable Energy Laboratory, University of Michigan, Ann Arbor, MI 48109-2145; Harbin Engineering University, Harbin 150001, China e-mail:
3. Marine Renewable Energy Laboratory; Department Naval Architecture and Marine Engineering, University of Michigan, Ann Arbor, MI 48109; Department Mechanical Engineering, University of Michigan, Ann Arbor, MI 48108; CTO Vortex Hydro Energy, University of Michigan, Ann Arbor, MI 48109-2145 e-mail: