Strouhal number for flying and swimming in rhinoceros auklets Cerorhinca monocerata
Strouhal number for flying and swimming in rhinoceros auklets Cerorhinca monocerata
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犀牛海雀飞行和游泳的斯特劳哈尔数 Cerorhinca monocerata
DOI：
10.1111/jav.00642
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发表时间：
2015
影响因子：
1.7
通讯作者：
Akinori Takahashi and Yuuki Y. Watanabe
中科院分区：
文献类型：
--
作者：
Dale M. Kikuchi ;Yutaka Watanuki ;Nobuhiko Sato ;Kenji Hoshina ;Akinori Takahashi and Yuuki Y. Watanabe
海雀通过在空气和水中拍打翅膀来推动自己，空气和水中的密度有很大的不同。我们假设，alcids改变翅膀的运动学，并保持斯特劳哈尔数（St=fA/U，其中fA是翅拍频率，A是翅拍幅度，和U是前进速度）在一定范围内，以实现有效的运动在飞行和游泳。我们使用加速度和GPS记录仪来测量自由放养的犀牛小海雀Cerorhinca monocerataduring飞行和游泳的翅膀跳动频率和前进速度。我们还测量了在野外拍摄的视频片段的翅振幅度。平均而言，翼拍频率，前进速度和翼拍幅度分别为8.9 Hz，15.3 m s-1和0.39 m，在飞行期间，和2.6 Hz，1.3 m s-1和0.18 m，分别在游泳期间。在游泳过程中，通过部分折叠翅膀，同时保持背腹翼拍角，可以实现较小的翼拍幅度。飞行时平均St为0.23，游泳时平均St为0.36。游泳的较高Stvalue可能与在水中推进所需的较高推力有关。我们的研究结果表明，犀牛小海雀的飞行和游泳的范围内（0.2-0.4），推进效率是已知的高Stin飞行专家和游泳专家收敛。
Alcids propel themselves by flapping wings in air and water that have vastly different densities. We hypothesized that alcids change wing kinematics and maintain Strouhal numbers (St=fA/U, wherefis wingbeat frequency,Ais the wingbeat amplitude, andUis forward speed) within a certain range, to achieve efficient locomotion during both flying and swimming. We used acceleration and GPS loggers to measure the wingbeat frequency and forward speed of free‐ranging rhinoceros aukletsCerorhinca monocerataduring both flying and swimming. We also measured wingbeat amplitude from video footage taken in the wild. On average, wingbeat frequency, forward speed, and wingbeat amplitude were 8.9 Hz, 15.3 m s−1, and 0.39 m, respectively, during flying, and 2.6 Hz, 1.3 m s−1, and 0.18 m, respectively, during swimming. The smaller wingbeat amplitude during swimming was achieved by partially folding the wings, while maintaining the dorso‐ventral wingbeat angle. MeanStwas 0.23 during flying and 0.36 during swimming. The higherStvalue for swimming might be related to the higher thrust force required for propulsion in water. Our results suggest that rhinoceros auklets maintainStfor both flying and swimming within the range (0.2–0.4) that propulsive efficiency is known to be high andStin both flying specialists and swimming specialists are known to converge.