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Katsuwonus pelamis : a case study in thunniform propulsion

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Title: Katsuwonus pelamis : a case study in thunniform propulsion
Author: Ben-Zvi, Micha
Degree Master of Science - MSc
Program Zoology
Copyright Date: 2011
Publicly Available in cIRcle 2011-07-12
Abstract: Thunniform propulsion is considered a case study in convergent evolution. Independently derived at least four times (whales, lamnid sharks, tunas and ichthyosaurs) it is characterized by uniquely high lift based thrust and efficient performance. As such it has been the focus of a great deal of study from not only biologists but engineers and physicists as well. Unfortunately direct physical measurement of this phenomenon is notoriously difficult to obtain. Therefore the majority of the research on the topic so far has consisted of either theoretical modeling or experimental testing with low bio-fidelity. The purpose of this study was to create a test apparatus that would more accurately mimic thunniform propulsion as seen in the study organism skipjack tuna (Katsuwonus pelamis). Such factors as motion parameters and swimming speeds as well as caudal fin size, shape and material properties were all taken into account and matched with in-vivo measurements. Instantaneous lateral and in-flow force measurements were taken throughout testing over a range of motion regimes. Overall, general motion parameter requirements for thrust generation were determined and quantified. Thrust production, of up to 0.42 N with a coefficient of thrust of approximately 0.2, was found to be in line with whole body drag estimates at tested conditions. Efficiency measurements however, were found to be extremely low (max of 35%) when compared to estimates in the literature of up to 90%. Quasi-static analysis was also conducted and shown to under-predict true thrust values by approximately 50%. A maximum coefficient of lift value was found to be approximately 0.55 at an angle of attack of 25° using this method.
URI: http://hdl.handle.net/2429/35971
Scholarly Level: Graduate

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