Mass-transport enhancement in regions bounded by rigid walls

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• 作者：Philip M.J. Trevelyan ; Serafim Kalliadasis ; John H. Merkin and Stephen K. Scott
• 关键词：mass ; transport enhancement ; diffusion ; effective diffusivity ; recirculation zone.
• 刊名：Journal of Engineering Mathematics
• 出版年：2002
• 出版时间：2002
• 年：2002
• 卷：42
• 期：1
• 页码：45-64
• 全文大小：211 KB

文摘

The mass transport into a fluid bounded by stationary rigid walls in the limit of large Péclet number, Pe, is examined analytically. Two model systems are considered in detail: a stationary cavity and a model involving two concentric rotating cylinders. A macroscopic gradient is imposed between the top and bottom surfaces. It is demonstrated that mass transport into the fluid is enhanced owing to a recirculation zone which is connected to the solid boundary through a boundary layer of thickness O(Pe–1/3) in which cross-stream molecular diffusion is balanced by convection. The associated enhancement is large and scales as Pe1/3. Our asymptotic analysis is found to be in good agreement with numerical solutions of the full transport equation.