Body-induced vortical flows: a common mechanism for self-corrective trimming control in boxfishes
Body-induced vortical flows: a common mechanism for self-corrective trimming control in boxfishes
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DOI：
10.1242/jeb.01356
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发表时间：
2005-01-01
影响因子：
2.8
通讯作者：
Gordon, MS
中科院分区：
文献类型：
--
作者：
Bartol, IK;Gharib, M;Gordon, MS
箱形鱼（硬骨鱼科：介形虫科）是具有坚硬甲壳的海洋鱼类，其形状和结构装饰在分类群中差异很大。我们之前展示了一种热带箱形鱼（光滑干鱼）的甲壳龙骨产生的前缘涡（LEVs）能够在游泳过程中产生自我纠正的修剪力。在本文中，我们证明了其他具有不同甲壳形状的热带箱鱼具有类似的能力。我们使用立体光刻术模型和三种独立但相互关联的分析方法：数字粒子图像测速（DPIV）、压力分布测量和力平衡测量，对三种形态不同的箱鱼（斑点箱鱼、涂鸦牛鱼和水牛干鱼）的甲壳周围的流动进行了定量研究。所有三种形式的腹龙骨都产生了lev，这些lev沿着身体循环生长，类似于三角翼飞机周围产生的lev。这些螺旋涡在龙骨上方形成并随着俯仰角的增大而增加，在龙骨下方形成并随着俯仰角的减小而增加。在所有箱鲀的眼脊上也形成了漩涡。在横截面呈梯形的斑点箱鲀中，眼脊后也存在一致的背涡生长。当三种箱鱼处于不同的偏航角度时，与近场区域相比，远场区域形成了最强的集中涡度区域，并且涡环流在质心后方最大。一般来说，局部低压区域与附着、集中涡量区域相关良好，尤其是在腹龙骨附近。尽管外壳的其他特征也以不同的方式影响流动模式和压力分布，但所有形式的流动的综合效果是一致的：它们产生修剪自校正力，我们使用力平衡直接测量。这些数据与之前对光滑干鱼的研究表明，身体诱导的涡旋流是一种常见的机制，可能对所有种类的热带箱鱼的修剪控制都有重要意义。
Boxfishes (Teleostei: Ostraciidae) are marine fishes having rigid carapaces that vary significantly among taxa in their shapes and structural ornamentation. We showed previously that the keels of the carapace of one species of tropical boxfish, the smooth trunkfish, produce leading edge vortices (LEVs) capable of generating self-correcting trimming forces during swimming. In this paper we show that other tropical boxfishes with different carapace shapes have similar capabilities. We conducted a quantitative study of flows around the carapaces of three morphologically distinct boxfishes (spotted boxfish, scrawled cowfish and buffalo trunkfish) using stereolithographic models and three separate but interrelated analytical approaches: digital particle image velocimetry (DPIV), pressure distribution measurements, and force balance measurements. The ventral keels of all three forms produced LEVs that grew in circulation along the bodies, resembling the LEVs produced around deltawinged aircraft. These spiral vortices formed above the keels and increased in circulation as pitch angle became more positive, and formed below the keels and increased in circulation as pitch angle became more negative. Vortices also formed along the eye ridges of all boxfishes. In the spotted boxfish, which is largely trapezoidal in cross section, consistent dorsal vortex growth posterior to the eye ridge was also present. When all three boxfishes were positioned at various yaw angles, regions of strongest concentrated vorticity formed in far-field locations of the carapace compared with near-field areas, and vortex circulation was greatest posterior to the center of mass. In general, regions of localized low pressure correlated well with regions of attached, concentrated vorticity, especially around the ventral keels. Although other features of the carapace also affect flow patterns and pressure distributions in different ways, the integrated effects of the flows were consistent for all forms: they produce trimming self-correcting forces, which we measured directly using the force balance. These data together with previous work on smooth trunkfish indicate that body-induced vortical flows are a common mechanism that is probably significant for trim control in all species of tropical boxfishes.