Drag on Two co-axial Rigid Spheres Moving Normal to a Plane: Newtonian and Carreau Fluids

藉著考慮兩相同之共軸剛性球在－牛頓及卡羅流體中垂直於－平板的運動，吾人探討了邊界效應與周邊粒子，在中及低雷諾數下，對－粒子沉降時所受拖曳力之影響。文中討論了系統之主要參數，包括流體特性、兩球間距離、較近球與平板間距離、與雷諾數等，與拖曳係數間的關係。數值模擬的結果顯示，邊界交應對拖曳係數的影響較流體特性與兩球間距離者為重要。卡羅流體中拖曳係數隨雷諾數變化的關係與牛頓流體中者類似，但前者中的剪致變稀特性有降低拖曳係數之效應。卡羅數夠大時，卡羅流體之指數參數的影響始較顯著。在雷諾數小於1的情況下，吾人獲得了拖曳係數與系統主要參數間的相關式。

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並列摘要

The boundary effect and the presence of a nearby entity on the drag of a rigid entity is investigated by considering the movement of two identical, rigid, coaxial spheres normal to a plane in both a Newtonian and a Carreau fluid at a low to medium large Reynolds number. The parameters key to the phenomenon under consideration, including the nature of the fluid, the separation distance between two spheres, the distance between the near sphere and the plane, and the Reynolds number, on the drag coefficient are discussed. We show that the influence of a boundary on the drag coefficient is more important than that of the nature of a fluid and that of the separation distance between two spheres. The variation of the drag coefficient as a function of Reynolds number for a Carreau fluid is similar to that for a Newtonian fluid, Due to the shear-thinning nature of the former the drag coefficient in the former is smaller than that in the latter, The influence of the index parameter of a Carreau fluid becomes appreciable only if the Carreau number is sufficiently large. Correlations between the drag coefficient and the key parameters of a system are developed for the case when the Reynolds number is smaller than 1.

並列關鍵字

Sedimentation ； Boundary effect ； Two coaxial rigid spheres normal to a plane ； Newtonian and Carreau fluid ； Drag coefficient

國際替代計量

Drag on Two co-axial Rigid Spheres Moving Normal to a Plane: Newtonian and Carreau Fluids

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