Numerical studies of the hysteresis in locomotion of a passively pitching foil

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• 作者：Xue-ming SHAO (邵雪明)^a ; ^{mecsxm@zju.edu.cn" class="auth_mail" title="E-mail the corresponding author}Author Vitae ; Xiao-long ZHANG (张晓龙)^a ; Zhao-sheng YU (余钊圣)^a ; ^{yuzhaosheng@zju.edu.cn" class="auth_mail" title="E-mail the corresponding author}
• 关键词：flapping foil ; passively pitching ; hysteresis ; fictitious domain method
• 刊名：Journal of Hydrodynamics, Ser. B
• 出版年：2016
• 出版时间：June 2016
• 年：2016
• 卷：28
• 期：3
• 页码：359-368
• 全文大小：2029 K

文摘

The direct-forcing fictitious domain method is extended to simulate the locomotion of a passively pitching foil. Our study focuses on the hysteresis phenomenon that the critical frequency for the reverse of the locomotion direction of the wing in case of decreasing frequency is smaller than that in case of increasing frequency. In our simulations, the hysteresis phenomenon is produced by imposing different initial conditions at a same frequency. Our results indicate that the ratio of the heaving amplitudes of two foil edges is crucial to the direction of the foil's horizontal motion, and the amplitude of the leading edge is generally smaller. The critical frequencies for the reverse of the locomotion direction are increased, when the foil-fluid density ratio is decreased or the spring constant is increased. The critical frequencies in the bi-stability regime also depend on the initial velocity imposed, and the hysteresis loop generally becomes larger if the initial velocities are closer to the terminal locomotion velocities of the foil.