熱泳效應對混合對流下拉伸孔隙壁質傳之影響

Effects of Thermophoresis on Mass Transfer in a Linearly Stretching Permeable Surface with Mixed Convection

黃建勝(J. S. Huang) ； 魏家鴻(C. H. Wei) ； 蔡瑞益(R. Tsai)

《先進工程學刊》 4卷4期 (2009/10) Pp. 390-396

https://doi.org/10.29948/JAE.200910.0012

摘要

本文探討當受到熱泳效應影響時，混合對流中拉伸孔隙壁的熱質傳遞現象。流體以二維混合對流邊界層流，流經一向上拉伸並包含吸附或吹離效應之垂直壁。統御方程式包括連續方程式、動量方程式、能量方程式及濃度場方程式，將統御方程式經過無因次化相似轉換過程後，數值計算方面以Runge-Kutta積分法求解。本文將針對溫度差的存在造成熱泳效應產生的影響做一詳細分析。當混合對流參數λ增加，流場速度梯度增加，而溫度場以及濃度場的邊界層相對減小，吸附作用的產生也將使得邊界層減小。壁温小於外在溫度時，微粒因熱泳效應影響，壁面濃度增加。而當壁温大於外在溫度時，粒徑越大者將隨溫度梯度增大而被吹離平板。

關鍵字

熱泳效應 ； 混合對流 ； 拉伸孔隙壁 ； 質量傳遞

並列摘要

A theoretical study of the effect of thermophoresis on heat and mass transfer by mixed convection from a linearly stretching permeable surface is reported. Consider the two-dimensional mixed convection boundary layer flow over a vertically moving upward surface with suction or blowing at the surface. The governing equations include the continuity, momentum, energy and concentration equations. The solution methods are used similarity transformation and dimensionless technique for the governing equations. In numerical analysis, the equations are solved by the Runge-Kutta integration method. When the mixed convection parameter λ increases, and the velocity gradient increases as well. Thermal and concentration boundary layer thickness decrease as λ increase. Boundary layer thickness also decreases with suction effect. The effect of thermophoresis was predicted to be particularity important for particles moving toward a cold surface or blowing away a hot surface at a given temperature gradient.

並列關鍵字

thermophoresis ； mixed convection ； stretching surface ； mass transfer