Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/1604
標題: 微通道流場中微粒運動之數值模擬
Numerical Simulation of Particle Motion in Microchannel Flows
作者: 莊裕豐
Chuang, Yufeng
關鍵字: particle;微粒;CMP;PIV;particle trajectories;粒子;化學機械研磨;速度量測系統;粒子運動軌跡
出版社: 機械工程學系
摘要: 
中文摘要
本研究之主要目的為探討微通道流場中,微粒之運動特性。微通道之寬度為80μm,其中具有一高度為入口寬度0.5或0.75倍之雲線形障礙物。流場之載運流體選擇為空氣或磨漿,且均滿足連續體之假設。此外流場控制於層流之範圍內。微粒則選擇為SiO2或Cu微粒,粒徑範圍為0.5nm至5μm。在本研究中,流場利用有限元素數值模式求得。而微粒之運動軌跡則由其初始位置為微通道入口處積分其運動方程式求得。
由於微粒於氣態流場及液態流場所受力量之量級,與微粒及流體之物理特性,如粒徑、密度,及粒子之Kn數等有關,故呈現不同之運動特性。在空氣流場中,由於粒子與流體之密度比甚大,故其運動主要受到阻力及布朗擴散運動之影響。大粒徑之微粒受阻力之影響較大,故出現撞擊流場壁面及障礙物之情形。而隨著粒徑之減少,粒子跟隨流場運動亦越明顯,惟布朗擴散運動之影響逐漸顯現。布朗運動亦可能造成微粒撞擊壁面之軌跡。
在磨漿流場中,由於微粒與流體之密度相當,故除阻力外,微粒之運動亦受重力、壓力梯度力及虛質力之影響,大粒徑之微粒,發現被捲入障礙物後方迴流區之軌跡。而粒徑減少時,發現粒子跟隨流場之運動。

Abstract
The major goal of the present study is to investigate the particle dynamics in a microchannel flow. The microchannel is composed by two parallel plates separated by a distance of 80μm. There is a spline-shaped obstacle attached on the lower wall of the channel with height of 40μm and 60μm. The carrier fluid are chosen to be air and slurry used in the CMP process. The flow inside the channel is assumed to be laminar and satisfies the continuum assumption. The motions of SiO2 and Cu particles, with diameters ranging from 0.5nm to 5μm, are to be studied in this flow field. The flow field is solved by finite element method, while the particle trajectories are obtained by integrating their equation of motion.
Due to the order of magnitude of forces acting on particle depend on the properties of particle and fluid such as particle diameter, density, and particle Knudsen number, the characteristics of particle motion in gaseous and liquid flow fields is fundamentally different. Due to large density ratio between particle and fluid, the dominant force of particle motion in air flow are drag and Brownian motion. For large particles, it is found that drag controls the motion of particles causing particle impingement on the walls and obstacle. For particle with diameters of order of 1nm, it is found that the effect of Brownian motion on particle motion becomes significant and particles have the chance to impinge on the walls.
In slurry flow field, gravity, pressure gradient force, and virtual mass force need to be included in the equation of particle motion in addition to drag force due to comparable densities between particle and fluid. For large particles, it is found that particle has the chance to be trapped into the recirculation zone behind the obstacle. However, the small particles exhibit the trajectories following closely with fluid motion.
URI: http://hdl.handle.net/11455/1604
Appears in Collections:機械工程學系所

Show full item record
 
TAIR Related Article

Google ScholarTM

Check


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.