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標題: | 微粒子影像測速儀應用於輪蟲運動的研究 Study on the motion of rotifer Philodina by Micro Particle Image Velocimetry |
作者: | Chen-Chou Ho 何承洲 |
指導教授: | 沈弘俊(Horn-Jiunn Sheen) |
共同指導教授: | 陳俊宏(Jiun-Hong Chen) |
關鍵字: | 纖毛,輪蟲,渦漩,旋輪蟲,推力, cilia,rotifer,vortex,Philodina,thrust, |
出版年 : | 2009 |
學位: | 碩士 |
摘要: | 縱古觀今,已有許多研究學者在仿生領域有許多學術上的研究貢
獻。諸如鳥飛魚游等大型動物的運動機制,但是鮮少有人去研究微生 物之運動機制方面的細節。而在本研究中,目的就是去探究旋輪蟲頭 冠上的纖毛擺動對流場所造成的影響,而此流場的影響又會對其運動 有怎樣的幫助或抑制。以纖毛所產生之流場結構、影響轉向的因素與 推進力量作為研究主軸,並探討與其他生物的運動做比較後的差異, 希望能更進一步了解旋輪蟲的運動行為。實驗分析是去量測旋輪蟲纖 毛擺動所產生之渦漩的速度向量場,並且進一步計算此相對應的推進 力量,來了解旋輪蟲是如何在水中進行此高效率且極富機動性的的游 泳運動。此外,在實驗過程中並無對旋輪蟲做任何的操控與限制,因 為旋輪蟲是一個極微小的微生物(長度100~400μm),而且對週遭環境極敏感。因此從微粒子影像測速儀量測及流場觀察中可以發現,兩個影響到旋輪蟲轉向的因素為渦漩對強度的差異和旋輪蟲蟲體自身的擺動扭曲。接著由定性的流場視覺化分析結果可知,旋輪蟲有三種不同的運動模態: (1) 輪蟲原地擺動纖毛不轉向 (2) 輪蟲原地擺動纖毛做順逆時針的轉向 (3) 輪蟲游動前進。三者皆以數位攝影機記錄其流場結構,並採用微粒子影像測速儀(micro-particle image velocimetry, μ-PIV)做定量的分析。μ-PIV流場的量測顯示渦漩對是由旋輪蟲的纖毛擺動所 產生的,且蟲體中央的推力是由於纖毛擺動產生一股往後的噴流所導 致。當旋輪蟲於原地擺動纖毛不轉向時,頭冠前方所產生的兩渦漩之 強度差異很小。當旋輪蟲於原地擺動且纖毛做順時針的轉向時,左前 方之渦漩的大小及強度皆大於右前方之渦漩,反之亦然。當旋輪蟲游 動前進時,一共會產生四個渦漩,除了前方兩渦漩外,亦會於蟲體兩 側產生兩個的渦漩,且在蟲體兩側的渦漩對之大小及強度也是大於前 方兩渦漩的。其中,頭冠前方所產生的渦漩對主要是幫助兩旁水流往 蟲體中央集中並朝向尾巴往後噴出,因此給予自身作用力而成為游泳 前進的主要推力。而蟲體兩側的渦漩主要是可以幫助旋輪蟲游動前 進,因為此兩渦漩減少了旋輪蟲在游泳過程中的摩擦阻力。輪蟲前進 最大的速度可達到5.17mm/s。經過計算後,可推知前進最大的推力可 達到0.197nN,所以每單位重量的最大推力為5.25μN/g。故旋輪蟲約需耗費此數量級的力量,才可將其尾巴固定在某一基質上。 Nowadays, there are many researches on the motion mechanism of fishes, birds and other animals, but few on tiny creatures has been investigated. The objective of this study is to understand the influence of cilia for a rotifer (Philodina) on its process of turning and swimming. We utilized micro-particle-image velocimetry (μ-PIV) to measure the velocity fields in vortecies which are induced by the cilia of Philodina and to evaluate the corresponding hydrodynamic force to know how can Philodina perform highly efficient and maneuverable swimming locomotion in the water. In addition, the experiments are carried out using nothing to limit the locomotion of Philodina because Philodina is a tiny creature (200~400μm in length) and is sensitive to environment. Therefore, the two factors to affect body-turning of Philodina are difference between strength of two vortices induced by cilia and body-turing. Both of them can not be eliminated. The qualitative flow visualization of vortices produced by Philodina show that there are three locomotion types. (1) position holding with cilia beating, (2) body-bending with cilia beating , (3) pure forward swimming. The flow field measurement by using μ-PIV shows that vortex pairs were generated by cilia of Philodina and the central jet force was produced as a result of cilia beating. When Philodina is at the same position with no body-bending, there is no significant difference between two front vortices generated from the corona cilia. While turning clockwise, size and strength of the left vortex produced by cilia of Philodina is larger than the right one, and vice versa. While swimming forward, the two lateral vortices are larger than front ones in size and strength. Moreover, the two front vortices help Philodina push fluid toward tail-like part and give reacting force to Philodina to become the main source of thrust and the two lateral vortices help Philodina swim forward because they decrease friction drag while Philodina is swimming. The maximum velocity of Philodina is 5.17mm/s and the maximum thrust is 0.197nN. Therefore the maximum thrust per unit weight is 5.25μN/g. Consequence, we can conclude that Philodina has to spend this kind level of force at to hold on the same place. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/41625 |
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