On the Underlying Drag-Reduction Mechanisms of Flow-Control Strategies in a Transitional Channel Flow: Temporal Approach
On the Underlying Drag-Reduction Mechanisms of Flow-Control Strategies in a Transitional Channel Flow: Temporal Approach
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过渡河道流中流量控制策略的潜在减阻机制：时间方法
DOI：
10.1007/s10494-021-00305-7
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Park, Jae Sung
中科院分区：
文献类型：
--
作者：
Rogge, Alexander J.;Park, Jae Sung
采用直接数值模拟的方法，在摩擦雷诺数为65 ~ 85的范围内，研究了三种不同的流动控制策略对槽道流动减阻效果的影响机理。这些策略包括添加长链聚合物、引入滑动表面和施加外部体积力。虽然人们认为这种方法通过控制近壁流动结构来减少表面摩擦，但起作用的基本机制仍然不清楚。在这项研究中，一个时间的分析，阐明这些方法之间的减阻机制。该分析基于间歇阶段的寿命，间歇阶段由最小湍流通道流的活动和休眠阶段代表（Xi和Graham，Phys Rev Lett 2010）。在相同减阻量下，聚合物法和滑移法显示出相似的减阻机理，而体积力法则不同。聚合物和滑动表面导致冬眠阶段更频繁地发生，而活动阶段的持续时间减少。然而，体积力导致冬眠阶段发生的频率较低，但延长其持续时间，以实现相当数量的减阻。体积力法背后的一个可能机制与其在壁面附近形成的独特的辊状旋涡结构有关。这些结构似乎可以防止内部和外部区域之间的相互作用，从而延长冬眠阶段。它应该激励自适应流动控制策略，以利用不同的基本机制，在低雷诺数的湍流阻力鲁棒控制。
The underlying mechanisms of three different flow-control strategies on drag reduction in a channel flow are investigated by direct numerical simulations at friction Reynolds numbers ranging from 65 to 85. These strategies include the addition of long-chain polymers, the incorporation of slip surfaces, and the application of an external body force. While it has been believed that such methods lead to a skin-friction reduction by controlling near-wall flow structures, the underlying mechanisms at play are still not as clear. In this study, a temporal analysis is employed to elucidate underlying drag-reduction mechanisms among these methods. The analysis is based on the lifetime of intermittent phases represented by the active and hibernating phases of a minimal turbulent channel flow (Xi and Graham, Phys Rev Lett 2010). At a similar amount of drag reduction, the polymer and slip methods show a similar mechanism, while the body force method is different. The polymers and slip surfaces cause hibernating phases to happen more frequently, while the duration of active phases is decreased. However, the body forces cause hibernating phases to happen less frequently but prolong its duration to achieve a comparable amount of drag reduction. A possible mechanism behind the body force method is associated with its unique roller-like vortical structures formed near the wall. These structures appear to prevent interactions between inner and outer regions by which hibernating phases are prolonged. It should motivate adaptive flow-control strategies to exploit the distinct underlying mechanisms for robust control of turbulent drag at low Reynolds numbers.
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影响因子：
3.7
作者：
Ethan A. Davis;J. S. Park
通讯作者：
Ethan A. Davis;J. S. Park
影响因子：
4.4
作者：
FLYVBJERG, H;PETERSEN, HG
通讯作者：
PETERSEN, HG
DOI：
10.3390/e22101126
发表时间：
2020-10-04
期刊：
Entropy (Basel, Switzerland)
影响因子：
--
作者：
Agrawal R;Ng HC;Davis EA;Park JS;Graham MD;Dennis DJC;Poole RJ
通讯作者：
Poole RJ
影响因子：
1.9
作者：
Ethan A. Davis;S. Mirfendereski;J. S. Park
通讯作者：
Ethan A. Davis;S. Mirfendereski;J. S. Park
湍流边界层中的相干结构
DOI：
10.1007/978-3-642-82994-9_5
发表时间：
1987
影响因子：
4.8
作者：
D. Coles
通讯作者：
D. Coles