Quantification of flows generated by the hydromedusa Aequorea victoria: a Lagrangian coherent structure analysis
Quantification of flows generated by the hydromedusa Aequorea victoria: a Lagrangian coherent structure analysis
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维多利亚水母产生的流量的量化：拉格朗日相干结构分析
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
J. Dabiri
中科院分区：
文献类型：
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作者：
K. Katija;Wesley T. Beaulieu;C. Regula;S. Colin;J. Costello;J. Dabiri
大多数扁水母利用游泳时产生的水流来捕捉猎物。量化它们与周围流体的相互作用对于理解它们的进食机制和开发预测其捕食影响的模型是必要的。在本研究中，我们量化了
水水母Aequorea维多利亚与其周围的流体和猎物相互作用。在实验室和自然场环境中，使用数字粒子图像测速（DPIV）测量的流体相互作用进行了检查。利用实验室DPIV数据计算了有限时间李雅普诺夫指数（FTLE）场，并从FTLE场中提取了拉格朗日相干结构（LCS）。实验室LCS分析表明，游泳A.维多利亚只遇到源自水母钟上游的离散流体包。根据这些数据包的大小，我们估计A。维多利亚的潜在清除量为11.4 l h^（-1）。结合测量的猎物捕获效率，我们估计潜在的清除率对不同的猎物类型。这些基于流体动力学的清除率估计值与先前测量的经验清除率估计值一致。速度矢量场和剪切场也表明，A.维多利亚可能比以前认为的更适合遇到桡足类。虽然仍然是初步的，在原位DPIV数据表明，自然背景流可能会改变遇到的过程中所观察到的静水实验室条件。
Most oblate medusae use flow generated during swimming to capture prey. Quantification of their interactions with surrounding fluid is necessary to understand their feeding mechanics and to develop models to predict their predatory impact. In the present study, we quantified how the
hydromedusa Aequorea victoria interacts with both its surrounding fluid and prey. The fluid interactions were examined in the laboratory and in natural field settings using digital particle image velocimetry (DPIV) measurements. The laboratory DPIV data were used to compute finite-time Lyapunov exponent (FTLE) fields, and Lagrangian coherent structures (LCS) were extracted from the FTLE fields. The laboratory LCS analysis demonstrated that swimming A. victoria only encounter discrete packets of fluid originating upstream of the medusan bell. Based on the size of these packets, we estimated that the A. victoria examined have the potential to clear 11.4 l h^(–1). Used in conjunction with measured prey capture efficiencies, we estimated potential clearance rates on different prey types. These hydrodynamically based clearance rate estimates are consistent with previously measured empirical clearance rate estimates. Velocity vector and shear fields also suggested that the feeding current created by A. victoria may be more suitable for encountering copepods than previously thought. Although still preliminary, in situ DPIV data indicate that natural background flows may alter the encounter process from what is observed in still-water laboratory conditions.