本文主要利用數值方法探討圓柱於剪切流中流體-彈性不穩定（Fluid-Elastic Instibility）之運動行為，理論模型則係基於暫態之連續與動量守恆方程式，並利用計算流體力學軟體FLUENT模擬圓柱在剪切流場中的運動行為，分析結果顯示圓柱在剪切流場中，同時具有渦漩引致振動及流體-彈性振動的特性。使用諧振模型（Harmonic Model）研究結果顯示，圓柱表面受剪切流橫向力之影響而產生側向升力，進而形成週期性的振動。而後探討剪切流內圓柱流體-彈性振動之振幅-對比速度的趨勢關係與運動軌跡，並解析不同剪切流速度梯度、阻尼係數等結構參數之影響，本文亦藉由FLUENT的動網格即時顯示功能，觀察圓柱移動時，網格重建（Remesh）的情形。

The present study aims to explore dynamical behavior of the fluid-elastic instability of a circular cylinder in shear flow by numerical simulations. The theoretical model comprises two groups of transient conservation equations of mass and momentum and the governing equations are solved numerically with Fluent software to determine the flow property. The analysis presented that there exist both vortex-induced vibration and flow-elastic vibration for single cylinder in sear flow. The numerical results with a Harmonic Model built from Gambit indicate that there is a transverse force acting from high velocity side toward the low velocity side in shear flow. The transverse force make cylinder move periodically and thus go to a vibration. Furthermore, this study appraises the amplitude and orbit of fluid elastic vibration of a circular cylinder in shear flow and shows the effects of the shear velocity slope and damping factor on fluid elastic vibration of the cylinder.
Here in the thesis, as the function applied with Fluent of displaying dynamic mesh on-time, the movement and re-mesh of cylinder could be observed. A vibration expansion diagram was presented and the pictures of flow velocity and flow pressure were retrieved from Fluent.

第一章 緒論------------------------------------------------------------------1
1.1 研究動機-------------------------------------------------------1
1.2 文獻回顧-------------------------------------------------------2
1.3 研究目的-------------------------------------------------------4
第二章 研究模式分析------------------------------------------------------6
2.1 理論分析-------------------------------------------------------6
2.1.1 流體統御方程式-----------------------------------------7
2.1.2 圓柱運動方程式---------------------------------------8
2.1.3數值運算流程----------------------------------------10
2.2 數值參數設定--------------------------------------------13

第三章 結果與討論----------------------------------------------------15
3.1 網格解析與時間間距設定---------------------------------17
3.2 結果分析------------------------------------------------------19
3.3 圓柱於剪切流場中的運動模式探討---------------------21
3.3.1 對比速度與振幅變化------------------------------21
3.3.2 剪切流速度梯度與振幅變化-------------------22
3.3.3 阻尼與振幅變化----------------------------23
3.3.4 圓柱振動軌跡變化---------------------------24
3.3.5圓柱於剪切流場中承受流體作用力分析---25
第四章 結論--------------------------------------------------------------28
參考文獻-------------------------------------------------------------------31

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