Measurements and analysis of force and moment of caudal fin model in C-start

Abstract The unsteady hydrodynamic forces and moments acting on caudal fin models of fish with different shapes and different swing durations were experimentally measured to simulate the fish C-starts. The motion of models was characterized by rotating the model to a maximum deflection angle in an excursion time Tu and back to the initial position in a return time Td around its root-axis. Studies show that the caudal-fin plays an important role in fish C-starts and the caudal-fins with different shapes and different swing duration generate different forces and moment. In addition, the hydrodynamic forces and moments acting on the models with different shapes can be normalized by the 2nd and 3rd moments of area, respectively. The forces and moments acting on the models with different swing durations, but the same ratio of Tu to Td can also be scaled. *Supported by National Natural Science Foundation of China (Grant No. 10332040) and the Knowledge Innovation Program of the Chinese Academy of Science (Grant ...