Shear flow of a Newtonian fluid over a quiescent generalized Newtonian fluid

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• 作者：Swati Mukhopadhyay ; Helge I. Andersson
• 关键词：Two ; fluid problems ; Interfacial coupling ; Shear ; driven flow ; Mixing ; layers ; Non ; Newtonian fluids ; Similarity solutions
• 刊名：Meccanica
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：52
• 期：4-5
• 页码：903-914
• 全文大小：
• 刊物类别：Physics and Astronomy
• 刊物主题：Classical Mechanics; Civil Engineering; Automotive Engineering; Mechanical Engineering;
• 出版者：Springer Netherlands
• ISSN：1572-9648
• 卷排序：52

文摘

The flow of an upper shear-driven Newtonian fluid above an otherwise still non-Newtonian fluid is considered. The lower fluid is modelled as a generalized Newtonian fluid and set into motion by interfacial shear. By means of similarity transformations, the governing partial differential equations for the two-fluid problem transform exactly into two sets of ordinary differential equations coupled only at the interface. The successful transformation of the two-fluid problem is applied to the particular case when the lower fluid obeys power-law rheology. The resulting three-parameter problem is solved numerically for some different parameter combinations by means of a direct integration approach with the density ratio fixed to unity. We observed that the interfacial velocities decreased with increasing values of the power-law index n in the range from 0.6 to 1.4 whereas the shear-induced motion of the lower fluid penetrates far deeper into a shear-thinning (n < 1) than into a shear-thickening (n > 1) fluid. This phenomenon is ascribed to a corresponding increase of the non-linear viscosity function with lower n-values.