運用邊界凸出效應以增強被動式菱形阻塊微混合器之混合效果

The Boundary Protrusion Effect on Mixing Enhancement of a Passive Micromixer with Diamond-shaped Obstacles

謝長豫(Chang-Yu Hsieh)

指導教授 ： 楊安石

國立臺北科技大學/機電學院/能源與冷凍空調工程系碩士班/碩士(2009年)

https://doi.org/10.6841/NTUT.2009.00220

摘要

如何達成有效率的混合對於許多運用於生物科技、分析化學以及醫學科技等相關領域的微流體裝置來說，是非常重要的。通常被動式微混合器靠著適當的流道幾何結構與放置於流道中之障礙物，可將流體分離與再次地結合，如此流體不但可減少擴散路徑更可增進混合的效能。
本研究目標為探討經由放置於混合器流道邊界之凸出結構物，以增強兩不同測試流體的混合效果。數值計算中，兩流體被視為、不可壓縮、可溶混層流，其特性固定且忽略重力的影響與溫度的變化。理論模型建立於三維暫態之質量、動量守恆方程式、及物種傳輸方程式；並採用迭代數值解法SIMPLEC演算法於求解統御方程式以計算各流場參數。不同軸向位置之所預測之混合效率結果將與相關文獻之測量結果作比對驗證。此外，另將詳細探究微混合器內混合發展過程之暫態流場及所需要之時間。研究結果指出邊界凸出物之鄰近區域呈現顯著的渦度產生，故沿著流場之方向增強其混合效率。為了獲得微混合器設計最佳化，數值實驗將進一步研究微混合器內邊界凸出物的寬度、長度、擺放之位置、及形狀對增強混合效率的影響。

關鍵字

微流體 ； 微混合器 ； CFD模擬

並列摘要

Effective mixing is of vital importance to many microfluidic devices with applications in the areas of biotechnical industries, analytic chemistry and medical industries. In practice, passive micromixers are dependent on the proper layout of channel geometric configurations with obstacles deposited in microchannels to break-up and recombine the flow as well as to reduce the diffusion path for improving the mixing performance. The objective of this study is to examine the mixing behavior of two test fluids flowing via a passive micromixer with protruded structures arranged at the boundary of the mixer. In simulations, both fluids were treated as laminar, incompressible, miscible, uniform-property liquid flows with negligible effects of gravity and temperature variation over the computational domain. The theoretical model was based on the time-dependent three-dimensional conservation equations of mass, momentum and species concentration; whereas, the governing equations were numerically solved using an iterative SIMPLEC algorithm to determine the flow/transport properties. The predicted mixing efficiency at different axial locations was compared with measured results in the literature for code validation. In addition, the present research explored the progression of the temporary mixing flowfield in a micromixer and the time required for realizing one mixing event in detail. The simulation results indicated that intense vortices were evidently induced in the boundary protrusion regions to augment the mixing efficiency along the flow course. To attain the design optimization of micromixers, numerical experiments were further extended to investigate the effects comprising height, width, spacing, and shape of boundary protrusion structures on mixing enhancement of a passive micromixer with diamond- shaped obstructions.

並列關鍵字

Microfluidics ； micromixer ； CFD simulations

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