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  • 學位論文

魚類群游游動性能之三維數值模擬與分析

Three-Dimensional Numerical Simulation and Analysis for Swimming Performance in Fish School

指導教授 : 楊鏡堂
本文將於2025/07/06開放下載。若您希望在開放下載時收到通知,可將文章加入收藏

摘要


本研究主旨是利用三維數值分析方法模擬群魚游動時,下游魚隻如何利用上游魚隻所產生的渦漩節能游動,也改變上游魚隻同相位與反相位擺動及增加z方向魚隻排列造成下游魚隻的影響。在群游實驗中非常難以拍攝觀察其流場,因此多以數值模擬為主要的探討方法,近年來多以二維數值模擬居多,但現實情況下群魚皆是三維排列,且其渦漩結構、傳遞速度及渦漩消散情況與二維排列截然不同,所以本研究使用三維模型來模擬群魚游動,使其流場結果更貼切現實情況。 本文利用上游兩魚隻帶領一隻下游魚隻進行模擬,以每0.1倍魚身長為間距做10組數據,得到當上下游魚隻列距為0.3倍魚身長時,上游魚隻所產生之渦漩射流方向與下游魚隻擺頭方向相同,下游魚隻可節省約13%的功率損耗,而當上下游魚隻列距為0.5倍魚身長時,上游魚隻所產生之渦漩射流方向與下游魚隻擺頭方向相反,下游魚隻則額外消耗11%的功率,說明擺頭方向與所對應渦漩射流方向之重要性。 當上游魚隻為同相位擺動時,兩上游魚隻所產生的渦漩射流的側向力方向相同,可以同時讓下游魚隻擺頭所使用,而當上游魚隻為反相位擺動時,兩上游魚隻所產生的渦漩環射流的側向力方向相反,會互相抵消,因此下游魚隻無法利用其能量進行擺頭,且上游魚隻反相位擺動閉合時,其尾鰭會對下游魚隻產生一射流,提高下游魚隻之阻力,使下游魚隻額外消耗約17%能量,因此推論群游游動較適合同相位擺尾。增加z方向魚隻排列與平面排列進行比較,結果得出有z方向魚隻排列時可節省約15%左右功率損耗,推力也有明顯的增加;從流場來看,可看出下游魚隻魚頭側面附近流速下降,使阻力下降,且產生渦漩的強度也增加,因此推力提升,而在自身推進模擬中得到群游游動有助於整體的極限速度提升,且增加z方向魚隻排列的下游魚隻加速度較快、推力較高,與定點擺動互相驗證在三維排列下,下游魚隻擁有較佳的游動表現。

並列摘要


In this study, a three-dimensional numerical simulation was applied to fish school by analyzing how the downstream fish use vortices produced by upstream fish to save power and also aimed at figuring out what impact on downstream fish caused by the change of in-phase and anti-phase swinging and the z direction arrangement by the upstream fish. Fish school’s flow field was very difficult to be observed through experiments; as a result, numerical simulation was applied for the main method to analyze. In recent years, a two-dimensional numerical simulation is more common, but in reality, the fish school is all of three-dimensional arrangement, and its vortices structure, vortices transmission speed and vortices dissipation are different from two-dimensional arrangement. Therefore, this study used a three-dimensional model to simulate the fish school, so that the flow field is more similar to reality. A numerical simulation of two upstream fish leading only one downstream fish was conducted, by using per one tenth of fish length to generate ten sets of data, when the distance between upstream fish and downstream fish is 0.3 time fish length, vortices direction produced by upstream fish is same as downstream fish’s head swinging direction, downstream fish can save about 13% power; when the distance between upstream fish and downstream fish is 0.5 time fish length, vortices direction produced by upstream fish and downstream fish’s head swing direction is in the opposite direction, downstream fish consumes 11% of the extra power. Therefore, it can explain the importance between the fish’s head swing direction and the vortices direction. When upstream fish school swings in-phase, two upstream fish produce vortices jet’s lateral force with same direction, so they can be used by downstream fish school for head swing; in the contrast, when upstream fish school swings anti-phase, two upstream fish produce vortices jet’s lateral force with opposite direction, they would offset each other, so they can’t be used by downstream fish school for head swing. Besides, caudal fin would produced one jet to downstream fish, it would cause downstream fish to suffer from resistance and consume extra 17% power to swim; therefore, fish school are suitable for swinging in-phase. In addition, z direction arrangement is compared with planar arrangement, the results show the former can save 15% power, and thrust force is significantly increases; the flow field shows that the downstream fish’s head side flow rate decreases, resistance decreases, and the vortices produced by downstream fish are enhanced, so the thrust force increases. In three-dimensional simulation self-propelled cases, the results show that limit speed are increased in fish school, and the downstream fish has faster acceleration and higher thrust force than planar arrangement. In conclusion, self-propelled cases and fixed-swing cases mutually authenticate that in three-dimensional arrangement, downstream fish have better swimming performance.

參考文獻


Alexander, R. M., "Hitching a lift hydrodynamically in swimming, flying and cycling, " Journal of Biological, 2004, Vol. 3, article 7.
Bleckmann H., and Zelick R., Lateral Line System of Fish, Integr. Zool., 2009, pp.13-15.
Blake R. W., "Hovering Performance of a Negatively Buoyant Fish," Canadian Journal of Zoology-Revue Canadienne De Zoologie, 1983, Vol. 61, pp. 2629-2630.
Breder C. M., "Studies on the Structure of the Fish School," Bulletin of the American Museum of Natural History, 1951, Vol. 98, pp. 1-27.
Chagnaud, B. P., Bleckmann, H. and Engelmann, J., "Neural responses of goldfish lateral line afferents to vortex motions, " Journal of Experimental Biology, 2006, Vol. 209, pp. 327-342.

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