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中文核心期刊

斑马鱼直线加速游动试验研究

EXPERIMENTAL STUDY OF ZEBRAFISH SWIMMING WITH LINEAR ACCELERATION

  • 摘要: 海洋生物低噪音、高速、髙效游动能力是任何人造水下航行器所无法比拟的. 借助时间解析粒子图像测速技术对斑马鱼直线加速游动过程进行精细流场测量, 对其运动学行为特性和动力学机理进行分析. 同时应用双正交分解对涡量场进行模态分解, 获取流场的时间演化和空间分布特征. 从流动机理的角度探究斑马鱼游动过程的流动结构特征及旋涡动态演化特性. 试验结果表明: 流动可视化展现了整体涡流尾迹的结构分布,方便探究运动特性与旋涡尾迹之间的耦合关系. 斑马鱼从运动开始时体干保持着鲹科式的运动规律, 游动时的动能主要由前几次大幅的摆尾过程提供, 后续的摆尾主要调整方向及姿态. 两次不同方向的摆尾动作会形成一对方向相反的旋涡, 并在时序下旋涡逐渐脱落. 同时尾流的涡量变化在一定程度上反映鱼体的游向的变化. 基于双正交分解分解后的时间演化结果验证本次试验在时间上涡量场具有合理的恒定幅度, 空间分布表明低阶空间模态表征斑马鱼游动的主要涡流动结构, 高阶空间模态表征涡流动的细节结构. 研究鱼类游动时的摆尾推进机制与动力学特性能够为高效率的仿鱼类推进装置设计提供一定科学参考.

     

    Abstract: The low-noise, high-speed and high-efficiency swimming ability of marine life is unmatched by any artificial underwater vehicle. With the help of time-resolved particle image velocimetry (TR-PIV), the fine flow field measurement of the zebrafish straight acceleration swimming process was carried out, and its kinematic behaviour characteristics and dynamic mechanism were analyzed. Meanwhile, bi-orthogonal decomposition (BOD) is applied to modal decomposition of the vorticity field, and the flow field's time evolution and spatial distribution characteristics are obtained. From the perspective of flow mechanism, the flow structure characteristics and the dynamic evolution characteristics of vortices during zebrafish swimming are explored. The results showed that: The flow visualization shows the structure distribution of the overall vortex wake, which is convenient to explore the coupling relationship between the motion characteristics and the vortex wake. From the beginning of the movement, all points on the body trunk of zebrafish maintain the wavy movement law. The first few large tail swings mainly provide kinetic energy during swimming, and the subsequent tail swings mainly adjust the direction and posture. Two tail swings in different directions will form a pair of vortices in opposite directions, and the vortices will gradually fall off under the timing sequence. Meanwhile, the change of the wake vorticity reflects the change of the swimming direction of the fish to a certain extent. Based on the time evolution results after BOD decomposition, it is verified that the vorticity field in this experiment has a reasonable constant amplitude in time. The spatial distribution indicates that the low-order spatial modes characterize the main vortex structure of zebrafish swimming, and the higher-order spatial modes characterize the detailed structure of the vortex flow. The research on the tail-swinging propulsion mechanism and the dynamic characteristics of fish during swimming can provide certain scientific value for designing high-efficiency fish-like propulsion devices.

     

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