(4)Fluid dynamics of a self-propelled biomimetic underwater vehicle with pectoral fins
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Ningyu Lia,l, Jiayuan Zhuanga,l,∗ , Yazhou Zhub,l, Guangsheng Sua, Yumin Sua
a Science and Technology on Underwater Vehicle Laboratory, Harbin Engineering University, Harbin, Heilongjiang 150001, China
b School of Naval Architecture & Ocean Engineering, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu 212003, China
Received 29 May 2020; received in revised form 23 August 2020; accepted 24 August 2020
Available online 8 September 2020
Abstract
Fluid dynamics of a self-propelled biomimetic underwater vehicle (BUV) with pectoral fins is investigated by an immersed boundary
(IB) method. Typically, the BUV with a pair of pectoral fins starts from rest and attains a constant mean velocity as the mean longitudinal
force is zero. The capability and accuracy of the IB method to deal with the interaction between the fluid and complex moving body are
firstly validated. Then we carry out a parametric study to understand the effect of key governing parameters on the dynamic response of
the BUV. It is found that with the increase of motion frequency or rolling amplitude, the pectoral fin propulsors can induce larger forward
velocity so that the BUV takes less time to attain its stable periodic swimming state. Although the pectoral fin is a very complicated lifting
surface, a linear relationship between forward Reynolds number (final swimming velocity is used as velocity scale) and frequency Reynolds
number (product of motion frequency and fin chord length is used as velocity scale) can be established when the frequency Reynolds number
is above a critical value. A linear relationship between forward Reynolds number and rolling amplitude is also found within the studied
range of rolling amplitude. Furthermore, a small-density-ratio BUV is sensitive to the surrounding flow with more rapid evolution process of
self-propulsion. Whereas, BUV with a large density ratio is more stable. The implications of the hydrodynamic analysis on the bio-inspired
engineering design of BUV with pectoral fins are also discussed.
© 2020 Shanghai Jiaotong University. Published by Elsevier B.V.
This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Keywords: Fluid dynamics; Self-propelled; Underwater vehicle; Pectoral fin; Immersed boundary method; Biomimetic.