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arXiv 1006.4598physics.flu-dynmath.OC
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通过流向行波控制turbulence的开始。部分2.直接数值模拟

Controlling the onset of turbulence by streamwise traveling waves. Part 2. Direct numerical simulations

Binh K. Lieu, Rashad Moarref, Mihailo R. Jovanović

摘要:

这项工作建立在并证实了本文第1部分的理论发现,Moarref & Jovanović(2010)。我们使用的纳维-斯托克斯方程的直接数值模拟来评估吹和吸的有效性,在流向行波的形式来控制通道流中的湍流的发生。我们强调修改后的基流的动态速度波动和净功率平衡的影响。我们的模拟验证了第1部分的理论预测,即上游行波促进湍流,即使当不受控制的流保持层流。另一方面,具有在第1部分中选择的参数的下游行波能够减小波动的动能,从而维持层流。在由固定压力梯度驱动的流动中,相对于不受控制的湍流,下游波可以实现高达25%的正净效率。此外,我们还发现,这些波也可以在低雷诺数下重新层化充分发展的湍流。我们的结论是,在第1部分中发展的理论的线性化流动方程的不确定性有相当大的能力来预测全尺寸的现象。

英文摘要:

This work builds on and confirms the theoretical findings of Part 1 of this paper, Moarref & Jovanović (2010). We use direct numerical simulations of the Navier-Stokes equations to assess the efficacy of blowing and suction in the form of streamwise traveling waves for controlling the onset of turbulence in a channel flow. We highlight the effects of the modified base flow on the dynamics of velocity fluctuations and net power balance. Our simulations verify the theoretical predictions of Part 1 that the upstream traveling waves promote turbulence even when the uncontrolled flow stays laminar. On the other hand, the downstream traveling waves with parameters selected in Part 1 are capable of reducing the fluctuations' kinetic energy, thereby maintaining the laminar flow. In flows driven by a fixed pressure gradient, a positive net efficiency as large as 25 % relative to the uncontrolled turbulent flow can be achieved with downstream waves. Furthermore, we show that these waves can also relaminarize fully developed turbulent flows at low Reynolds numbers. We conclude that the theory developed in Part 1 for the linearized flow equations with uncertainty has considerable ability to predict full-scale phenomena.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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