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《应用数学和力学(英文版)》 2018-09
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Direct numerical simulation of turbulent flows through concentric annulus with circumferential oscillation of inner wall

Yichen YAO;Chunxiao XU;Weixi HUANG;Department of Engineering Mechanics, Tsinghua University;  
Periodic wall oscillations in the spanwise or circumferential direction can greatly reduce the friction drag in turbulent channel and pipe flows. In a concentric annulus, the constant rotation of the inner cylinder can intensify turbulence fluctuations and enhance skin friction due to centrifugal instabilities. In the present study, the effects of the periodic oscillation of the inner wall on turbulent flows through concentric annulus are investigated by the direct numerical simulation(DNS). The radius ratio of the inner to the outer cylinders is 0.1, and the Reynolds number is 2 225 based on the bulk mean velocity Um and the half annulus gap H. The influence of oscillation period is considered. It is found that for short-period oscillations, the Stokes layer formed by the circumferential wall movement can effectively inhibit the near-wall coherent motions and lead to skin friction reduction, while for long-period oscillations, the centrifugal instability has enough time to develop and generate new vortices, resulting in the enhancement of turbulence intensity and skin friction.
【Fund】: Project supported by the National Natural Science Foundation of China(No.11490551)
【CateGory Index】: O357.5
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