多孔介質內具有非均勻表面溫度與濃度之任意傾斜板的雙重擴散自然對流

Double-Diffusive Free Convection over Arbitrarily Inclined Plates with Nonuniform Surface Temperature and Concentration in Porous Media

本文研究充滿流體的多孔介質內任意傾斜板之雙重擴散自然對流，而且此一傾斜板具有非均勻表面溫度與濃度。統制方程式先被轉換為一組非相似微分方程式，再以以三次樣條配置法解所得的邊界層方程式。熱與質量傳遞的特性呈現為下列參數之函數：表面溫度指數、表面濃度指數、傾斜變數、路易斯數與浮力比。結果顯示，增大路易斯數時，局部紐塞數會減少，而局部雪耳伍德數會增加。對正傾斜情況而言，隨著傾斜變數之增大，局部紐塞數與局部雪耳伍德數會先減少，到達最小值後再變大。此最小值發生在浮力之切線方向與法線方向之分量一樣大時。

This work studies the double-diffusive free convection over arbitrarily inclined plates in fluid saturated porous media with nonuniform surface temperature and concentration. The governing equations are transformed into a set of nonsimilar differential equations, and the obtained boundary layer equations are then solved by the cubic spline collocation method. The heat and mass transfer characteristics are presented as functions of surface temperature exponent, surface concentration exponent, inclination variable, Lewis number, and buoyancy ratio. Results show that an increase in the Lewis number leads to a decrease in the local Nusselt number and an increase in the local Sherwood number. Moreover, increasing the buoyancy ratio tends to increase both the local Nusselt number and the local Sherwood number. For the positive inclination, as the inclination variable increases, the local Nusselt number and the local Sherwood number first decrease, reach minima, and then increase. The minima are where the tangential and normal components of buoyancy force are comparable.