文章基本信息

标题：Motion of Passive Scalar by Elasticity-Induced Instability in Curved Microchannel:
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作者：Xiao-Bin Li ; Hong-Na Zhang ; Yang Cao 等
期刊名称：Advances in Mechanical Engineering
印刷版ISSN：1687-8140
电子版ISSN：1687-8140
出版年度：2014
卷号：6
页码：1-10
DOI：10.1155/2014/734175
语种：English
出版社：Sage Publications Ltd.
摘要：This paper presented a direct numerical simulation (DNS) study on the elasticity-induced irregular flow, passive mixing, and scalar evolution in the curvilinear microchannel. The mixing enhancement was achieved at vanishingly low-Reynolds-number chaotic flow raised by elastic instabilities. Along with the mixing process, the passive scalar transportation carried by the flow was greatly affected by the flow structure and the underlying interaction between microstructures of viscoelastic fluid and flow structure itself. The simulations are conducted for a wide range of viscoelasticity. As the elastic effect exceeds the critical value, the flow tends to a chaotic state, while the evolution of scalar gets strong and fast, showing excellent agreement with experimental results. For the temporal changing of scalar gradients, they vary rapidly in the form of isosurfaces, with the shape of “rolls” in the bulk and evolving into “threads” near the wall. That indicates that the flow fields should be related to the deformation of viscoelastic micromolecules. The probability distribution function analysis between micromolecular deformation and flow field deformation shows that the main direction of molecular stretching is perpendicular to the main direction of flow field deformation. It implies they are weakly correlated, due to the confinement of channel wall.