Controlling secondary flows in Taylor–Couette flow using axially spaced superhydrophobic surfaces
Controlling secondary flows in Taylor–Couette flow using axially spaced superhydrophobic surfaces
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DOI：
10.1017/jfm.2023.606
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发表时间：
2023-08
影响因子：
3.7
通讯作者：
Vignesh Jeganathan;Tala Shannak;K. Alba;Rodolfo Ostilla-Mónico
中科院分区：
文献类型：
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作者：
Vignesh Jeganathan;Tala Shannak;K. Alba;Rodolfo Ostilla-Mónico
摘要湍流剪切流广泛存在于地球物理和天体物理系统以及工程技术应用中。它们经常充斥着大规模的二次流，这些二次流极大地改变了主流的特性，防止或加强了混合、传质和热传递。通过实验和数值模拟，我们研究了通过使用超疏水表面处理来降低局部剪切来改变这些二次流的可能性。我们专注于Taylor-Couette流的正则问题，即两个同轴和独立旋转的圆柱体之间的流动，它具有坚固的二次结构，称为Taylor Rolls，即使在显著的湍流水平上也仍然存在。我们只通过旋转系统的内筒来产生这些结构，并证明了轴向间隔的超疏水处理可以通过不匹配的表面不均匀来削弱辊，只要辊的尺寸可以固定。对这种流动控制所需处理的最小疏水性进行了合理化，并讨论了其在本文所研究的雷诺数之外的有效性。
Abstract Turbulent shear flows are abundant in geophysical and astrophysical systems and in engineering-technology applications. They are often riddled with large-scale secondary flows that drastically modify the characteristics of the primary stream, preventing or enhancing mixing, mass and heat transfer. Using experiments and numerical simulations, we study the possibility of modifying these secondary flows by using superhydrophobic surface treatments that reduce the local shear. We focus on the canonical problem of Taylor–Couette flow, the flow between two coaxial and independently rotating cylinders, which has robust secondary structures called Taylor rolls that persist even at significant levels of turbulence. We generate these structures by rotating only the inner cylinder of the system, and show that an axially spaced superhydrophobic treatment can weaken the rolls through a mismatching surface heterogeneity, as long as the roll size can be fixed. The minimum hydrophobicity of the treatment required for this flow control is rationalized, and its effectiveness beyond the Reynolds numbers studied here is also discussed.