Simulations of laminar flow past a superhydrophobic sphere with drag reduction and separation delay
Simulations of laminar flow past a superhydrophobic sphere with drag reduction and separation delay
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DOI：
10.1063/1.4801450
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发表时间：
2013-04-01
影响因子：
4.6
通讯作者：
McHale, Glen
中科院分区：
文献类型：
--
作者：
Gruncell, Brian R. K.;Sandham, Neil D.;McHale, Glen
超疏水表面具有通过结合结构化表面和疏水性以在表面处保留润滑空气层（胸甲）来减少流体动力学阻力的潜力。在目前的贡献，数值模拟层流通过超疏水球进行使用两相流表示。结果表明，空气-水系统中斯托克斯流的阻力降低高达19%，与以前的分析工作一致，并表明随着雷诺数增加到100，效果会增加。由于减少了粘性阻力和抑制了胸甲的分离，导致尾流变窄，从而实现了高达50%的阻力减少。为了探索一个不太理想化的模型的胸甲，挡板也被引入到模拟的胸甲的粗糙度元素的支持。折流板导致附着涡区不再被抑制，但分离被延迟，与实心球相比，阻力减小是明显的。增加面积固体分数导致由于腹板而减小的阻力减小，然而，在固体分数为10%的情况下仍然可以实现高达15%的阻力减小。(C)2013 AIP Publishing LLC. [http：//dx.doi.org/10.1063/1.4801450]
Superhydrophobic surfaces have potential for reducing hydrodynamic drag by combining a structured surface and hydrophobicity to retain a lubricating air layer (plastron) at the surface. In the present contribution, numerical simulations of laminar flow past a superhydrophobic sphere are conducted using a two-phase flow representation. The results show drag reductions in Stokes flow of up to 19% for an air-water system, in agreement with previous analytic work, and demonstrate an increased effect as the Reynolds number is increased to 100. Drag reductions of up to 50% are achieved due to reduction in viscous drag and suppression of separation by the plastron, resulting in a narrower wake. To explore a less idealised model of the plastron, baffles have also been introduced to simulate the support of a plastron by roughness elements. The baffles lead to the attached vortex regime no longer being suppressed, but separation is delayed and drag reductions are evident in comparison to a solid sphere. Increasing the area solid fraction results in a diminished drag reduction due to the plastron, however drag reductions of up to 15% can still be achieved with solid fractions of 10%. (C) 2013 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4801450]