自Strouhal發現流場中的圓柱產生渦流溢放現象之後，流體力學在其理論上的推導及工程上的應用皆有相當的發展。而鈍形體表面流場的研究始終為許多專家熱衷的研究課題之一，其原因乃是其空氣動力特性，不論在航空、土木、建築、海洋、量測等工程領域，均有重要之應用。圓柱流場是個複雜且經典的流體力學基本問題，均勻流通過圓柱後常見上下搖擺的渦流溢放現象，這是尾部渦流上下交互作用，導致的週期性變化。然而渦流溢放現象常在我們的日常生活裡發生，就如同飛機翼後渦流的形成及電塔鋼索的震盪；近年來，如何改善渦流溢放現象一直是受到許多研究人員所重視的課題，而利用開縫圓柱來改善渦流溢放現象研究也行之有年，但甚少有人探討開縫圓柱中角度對於其流場特性之影響。本研究希望藉由改變開縫圓柱的角度，探討其對渦流溢放現象造成影響。

Ever since Strouhal’s discovery of Vortex Shedding Phenomenon in the circular cylinder in a flow field, the development of fluid mechanics in its theoretical deduction and application in engineering has shown significant growth. The study on the flow field of the surface of blunt body has remained one of the most popular research topics among the professionals. The key reason is its aerodynamic characteristics and the application in engineering fields such as aerospace engineering, civil engineering, construction, ocean engineering and measurement. The flow field of circular cylinder is a classic yet complicated question of fluid mechanics. Vortex Shedding Phenomenon, an oscillating flow occurred because of the cross interaction of vortices at the bottom of cylinder when the flows past the circular cylinder. The Vortex Shedding Phenomenon can be easily observed in our everyday life. For example, the swirling flow of air produced behind the airplane wings and the vibration of steel cables in electrical towers. Researchers have been working hard in recent years to suppress the phenomenon of vortex shedding. The research on reduction of vortex shedding phenomenon by adopting circular cylinder with silt has been studied for years. However, few researchers study the effect of changes of the angle of circular cylinder with silt on its flow field characteristics. Therefore, this research aims to investigate the phenomenon of vortex shedding being affected by the changes of the angle of circular cylinder with silt.

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