上板拉升之不可互溶Hele-Shaw流場數值模擬

Abstract

LOCA為一台利用壓合力量，使兩平板中間含有OCR材質之膠體均勻地流佈，進而使兩平板最終能夠密合。為達此目的，吾人希望得到最初點膠時中心膠體的形狀，使得當上平板下壓時，膠體擴散到達邊界時能夠一致，其最終形狀能與基板相同，膠體分佈厚度平均且減少溢膠的情況發生。在先前關於Hele-Shaw不可互溶流場模擬的研究中，大多著重在上板拉升的情況下，當上平板拉升時兩平板間的流體會向內凹陷，這與我們上述的情況是相反的，因此吾人假設上板拉升後的圖形將會是上板下壓的最初圖形，利用上板拉升之不可互溶Hele-Shaw cell的數值模擬來研究此問題。我們發現當上板拉升時，原始圖形為矩形之內流體，隨著拉升高度增加，其矩形四邊會快速地向內凹陷，而四角也會緩慢地往內縮，最終在矩形四個角形成不穩定之指狀物圖形。

The LOCA coating machine uses stress to force two plates where OCR material is placed between close-fitting. The glue optimal pattern spreads close to its base plate and no glue should excess the plate boundary. The processes mimic the problems of compressing Hele-Shaw flows. Accordingly, we assume that the inner flow pattern formed from the pulled plate is same as the original figure which upper plate pushed down. In this study, we use computer simulation method to find out that how the viscosity ratio, the initial aspect ratio, the lifting plate velocity and the surface tension induce the optimization of glue pattern. As the result of interfacial instability, less viscous fluid displaces another fluid of higher viscosity while the height increasing. Four sides of the rectangle will rapidly shrink inward. On the contrary, the pattern will appear four fingers on the corner of the rectangle.