臺灣博碩士論文加值系統

本研究使用商業計算軟體(CFDRC)，來模擬去離子水和剪切稀化流體(羧甲基纖維素水溶液)在以下的微混合器中的流動與混合行為：具固定曲率半徑之蜿蜒流道，具步階式增減曲率半徑之蜿蜒流道及擁有漸縮漸擴截面積之蜿蜒流道。本研究探討在這些微混合器中，幾何尺寸對於流動與混合行為的影響。接著，比較去離子水與剪切稀化流體在等截面積之蜿蜒流道中流動的情形。最後，觀察較高流速下，剪切稀化流體於等截面積之蜿蜒流道內的狄恩不穩定性。從模擬的結果，可以得到以下的結論：(一)具漸縮漸擴寬度之蜿蜒流道會產生分離渦流，因此增進流體的混合。(二)剪切稀化流體在具漸縮漸擴截面之蜿蜒流道會有較小的表象黏滯係數。(三)由於狄恩不穩定性所生成之狄恩渦流會大幅地增進流體的混合。

In this work, we use commercial codes (CFDRC) to simulate the flow and mixing behaviors of DI water and shear-thinning fluids (aqueous solution of Carboxymethyl Cellulose) in the following micromixers：serpentine channel with constant curvature radius, serpentine channel with stepwise increasing and decreasing curvature radiuses and serpentine channel with converging-diverging cross section. We investigate the effect of geometry on the flow and mixing behaviors in these micromixers. We also compare the flow of DI water and shear-thinning fluids in serpentine channels with constant cross section area. Finally, we observe the Dean instability of the flow in serpentine channel with constant cross section for shear-thinning fluids with high velocity. From the simulation results, we have the following conclusions：(1) The converging-diverging width of serpentine channel causes separation vortex and so enhances fluid mixing. (2) Shear-thinning fluids in serpentine channels with converging-diverging section area shows a smaller average apparent viscosity. (3) The Dean vortexes due to instability considerably improves fluid mixing.

摘要 i
Abstract ii
目錄 iii
表目錄 v
圖目錄 vi
符號表 xvi
第一章 緒論 1
1-1 研究背景 1
1-2 文獻回顧 1
1-3 研究動機 3
1-4 本文架構 4
第二章 流道外形設計與數值模擬 5
2-1 微混合器之幾何尺寸 5
2-1-1 具固定曲率半徑之蜿蜒流道 5
2-1-2 具步階式增減曲率半徑之蜿蜒流道 5
2-1-3 具漸縮漸擴截面積之蜿蜒流道 6
2-2 基本假設 6
2-3 統御方程式 7
2-4 邊界條件 8
2-5 無因次化分析 9
2-5-1 方程式的無因次化 9
2-5-2 邊界條件的無因次化 11
2-6 數值模擬 11
2-6-1 CFD-GEOM 繪出微混合器之幾何形狀與網格建立 11
2-6-2 以CFD-ACE+ 做模擬運算 12
2-6-3 以CFD-VIEW 做後處理 12
2-7 混合度 13
第三章 結果與討論 14
3-1 簡介 14
3-2 網格測試與文獻佐證 14
3-3固定曲率半徑和步階式增減曲率半徑對於等截面積蜿蜒流道中牛頓流體流動與混
合的影響 17
3-4剪切稀化流體在等截面積和漸縮漸擴截面積之蜿蜒流道中流動與混合之比較
21
3-5剪切稀化流體於等截面積之蜿蜒流道內狄恩不穩定性以及其對混合影響之探討
27
第四章 結論與未來展望 29
4-1 結論 29
4-2 未來展望 29
參考文獻 30

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