Liu Weixing, Li Ningyu, Zhao Jinxin, Su Yumin
Science and Technology on Underwater Vehicle Laboratory, Harbin Engineering University, Harbin 150001, China.
Beijing Machine and Equipment Institute, Beijing 100854, China.
Saudi J Biol Sci. 2017 Sep;24(6):1344-1354. doi: 10.1016/j.sjbs.2016.09.015. Epub 2016 Sep 12.
Numerical simulations are used to investigate the wake structure and hydrodynamic performance of bionic flapping foils. The study is motivated by the quest to understand the fluid dynamics of fish fins and use it in the underwater propulsion. The simulations employ an immersed boundary method that makes it possible to simulate flows with complex moving boundaries on fixed Cartesian grids. A detailed analysis of the vortex topology shows that the wake of flapping foils is dominated by two sets of complex shaped vortex rings that convect at oblique angles to the wake centerline. The wake of these flapping foils is characterized by two oblique jets. Simulations are also used to examine the wake vortex and hydrodynamic performance over a range of Strouhal numbers and maximum pitch angles and the connection between the foil kinematics, vortex dynamics and force production is discussed. The results show that the variety law of the hydrodynamic performance with kinematic parameters strongly depends on the flow dynamics underlying the force production, including the orientation, interconnection and dissipation rate of the vortex rings.
数值模拟用于研究仿生扑翼的尾流结构和水动力性能。该研究旨在理解鱼鳍的流体动力学并将其应用于水下推进。模拟采用浸入边界方法，使得在固定笛卡尔网格上模拟具有复杂移动边界的流动成为可能。对涡旋拓扑的详细分析表明，扑翼的尾流由两组复杂形状的涡环主导，它们以倾斜角度向尾流中心线对流。这些扑翼的尾流以两个倾斜射流为特征。模拟还用于研究在一系列斯特劳哈尔数和最大俯仰角范围内的尾流涡旋和水动力性能，并讨论了翼型运动学、涡旋动力学和力产生之间的联系。结果表明，水动力性能随运动学参数的变化规律强烈依赖于力产生背后的流动动力学，包括涡环的取向、相互连接和耗散率。
