具有雙面閃電型凹槽微流道之流場與濃度場分析

本論文探討流體在經過微混合器中閃電形凹槽微結構時的混合特徵，並對微流道中產生之流動現象進行研究。此微混合器是利用流道的上下面佈置閃電形凹槽，以產生混沌移流的混合效應；閃電形凹槽設計以45°斜線，在流道寬三分之二處產生90°之轉角，形成像閃電般的凹槽，使流體產生迴流的現象。利用截面速度向量圖、煙線圖、截面濃度分佈圖等，探討不同幾何參數的影響，了解各參數對微流體混合效率的影響。當流道中佈置閃電形凹槽時，可使液體產生很強的側流作用，在傾斜45度的斜邊上增添90度的轉角，能使液體流經此轉角產生液體迴流現象，可增加液體間的接觸面積。經由設計不同的參數來探討迴流現象對混合的特徵，結果顯示在雷諾數低時，凹槽和流道的深度比為1：2、轉角距離為30μm，可得到較好的混合效應。以微機電製程製作出具有不同幾何參數的微流道，以光學顯微鏡觀測兩種流體在流道中的混合現象，實驗的結與果模擬的結果進行比較，結果顯示在具有閃電形凹槽和斜直形凹槽的流道中，墨水溶液會被帶往去離子水所在的區塊進行混合。具有斜直形凹槽的流道僅讓流體順著凹槽移動，產生側向流；而具有閃電形凹槽的流道，不但能讓流體產生側向流，亦可在凹槽轉角處使流體產生迴流現象。

關鍵字

閃電形凹槽；混沌移流；煙線

並列摘要

This study utilizes the numerical simulations to discuss the flow and mixing characteristics whereas the pressure-driven flow passes through the microchannel with lightning-grooved microstructures. The lightning grooves at the top and/or bottom side of the floors in the micromixer are placed to generate the chaotic advection. The lightning grooves are designed by setting the oblique straight grooves at the angle of 45°, and creating the right angle corner at the 2/3 width of the channel. And then the influences of various geometric parameters on mixing in terms of velocity vector diagram, streak line diagram and cross-sectional concentration distribution are investigated. A stronger transverse flow is created by placing the lightning grooves on the floors. At Reynolds numbers of 1-50, vortex flows can be induced at the corners of the grooves with the lightning grooves on the floors, and it can increase the contact areas between fluids in the corners. The results demonstrate that whereas the ratio of groove depth and channels depth is less than 1/2 and the offset of the grooves is at 35 μm, the mixing effect can be improved with the Re increasing.

並列關鍵字

lightning grooves ； vortex flow ； streak line

參考文獻

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具有雙面閃電型凹槽微流道之流場與濃度場分析

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