Multi-camera volumetric PIV for the study of jumping fish
Multi-camera volumetric PIV for the study of jumping fish
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DOI：
10.1007/s00348-017-2468-x
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发表时间：
2017
影响因子：
2.4
通讯作者：
Leah Mendelson;A. Techet
中科院分区：
文献类型：
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作者：
Leah Mendelson;A. Techet
箭鱼能准确地从自由水面下跳跃多个身长来捕捉空中猎物。多个鳍提供推进和稳定的组合，使猎物能够成功捕获。在这种高度三维的机动过程中，体积流场测量是表征多推进器相互作用的关键；然而，鱼的行为也带来了独特的实验限制。测量必须在靠近水面和部分被鱼体遮挡的流场区域进行。空中跳跃轨迹也必须知道，以评估性能。本文介绍了三维合成孔径粒子图像测速（SAPIV）技术的实验设置和处理修改，以解决这些挑战，并促进对活跳鱼的实验测量。分析了传统SAPIV算法在部分遮挡区域的性能，提出了一种改进的物体周围SAPIV算法的非迭代重建方法。这种重建过程与自由表面两侧的三维成像相结合，揭示了鱼的三维尾迹，包括由尾巴产生的一系列推进涡旋环。此外，来自肛门和背鳍的尾流测量表明，它们在箭鱼跳跃时起到了稳定和产生推力的作用。
Archer fish accurately jump multiple body lengths for aerial prey from directly below the free surface. Multiple fins provide combinations of propulsion and stabilization, enabling prey capture success. Volumetric flow field measurements are crucial to characterizing multi-propulsor interactions during this highly three-dimensional maneuver; however, the fish’s behavior also drives unique experimental constraints. Measurements must be obtained in close proximity to the water’s surface and in regions of the flow field which are partially-occluded by the fish body. Aerial jump trajectories must also be known to assess performance. This article describes experiment setup and processing modifications to the three-dimensional synthetic aperture particle image velocimetry (SAPIV) technique to address these challenges and facilitate experimental measurements on live jumping fish. The performance of traditional SAPIV algorithms in partially-occluded regions is characterized, and an improved non-iterative reconstruction routine for SAPIV around bodies is introduced. This reconstruction procedure is combined with three-dimensional imaging on both sides of the free surface to reveal the fish’s three-dimensional wake, including a series of propulsive vortex rings generated by the tail. In addition, wake measurements from the anal and dorsal fins indicate their stabilizing and thrust-producing contributions as the archer fish jumps.