Applied Mathematics and Mechanics (English Edition) ›› 2019, Vol. 40 ›› Issue (4): 435-448.doi: https://doi.org/10.1007/s10483-019-2471-7

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Numerical study of the turbulent channel flow under space-dependent electromagnetic force control at different Reynolds numbers

Daiwen JIANG1, Hui ZHANG1,2, Baochun FAN1, Zijie ZHAO1, Jian LI1, Mingyue GUI1   

  1. 1. Science and Technology on Transient Physics Laboratory, Nanjing University of Science and Technology, Nanjing 210094, China;
    2. Department of Mathematics, Imperial College London, London SW72AZ, U.K
  • 收稿日期:2018-04-24 修回日期:2018-10-11 出版日期:2019-04-01 发布日期:2019-04-01
  • 通讯作者: Hui ZHANG E-mail:zhanghui1902@hotmail.com
  • 基金资助:

    Project supported by the National Natural Science Foundation of China (No. 11672135) and the Foundation for the Author of National Excellent Doctoral Dissertation of China (No. 201461)

Numerical study of the turbulent channel flow under space-dependent electromagnetic force control at different Reynolds numbers

Daiwen JIANG1, Hui ZHANG1,2, Baochun FAN1, Zijie ZHAO1, Jian LI1, Mingyue GUI1   

  1. 1. Science and Technology on Transient Physics Laboratory, Nanjing University of Science and Technology, Nanjing 210094, China;
    2. Department of Mathematics, Imperial College London, London SW72AZ, U.K
  • Received:2018-04-24 Revised:2018-10-11 Online:2019-04-01 Published:2019-04-01
  • Contact: Hui ZHANG E-mail:zhanghui1902@hotmail.com
  • Supported by:

    Project supported by the National Natural Science Foundation of China (No. 11672135) and the Foundation for the Author of National Excellent Doctoral Dissertation of China (No. 201461)

摘要:

In this paper, the control of turbulent channel flow by space-dependent electromagnetic force and the mechanism of drag reduction are investigated with the direct numerical simulation (DNS) methods for different Reynolds numbers. A formulation is derived to express the relation between the drag and the Reynolds shear stress. With the application of optimal electromagnetic force, the in-depth relations among characteristic structures in the flow field, mean Reynolds shear stress, and the effect of drag reduction for different Reynolds numbers are discussed. The results indicate that the maximum drag reductions can be obtained with an optimal combination of parameters for each case of different Reynolds numbers. The regular quasi-streamwise vortex structures, which appear in the flow field, have the same period with that of the electromagnetic force. These structures suppress the random velocity fluctuations, which leads to the absolute value of mean Reynolds shear stress decreasing and the distribution of that moving away from the wall. Moreover, the wave number of optimal electromagnetic force increases, and the scale of the regular quasi-streamwise vortex structures decreases as the Reynolds number increases. Therefore, the rate of drag reduction decreases with the increase in the Reynolds number since the scale of the regular quasi-streamwise vortex structures decreases.

关键词: drag reduction, composite materials, laminated plates, dynamic stability, flow control, turbulent channel flow, electromagnetic force

Abstract:

In this paper, the control of turbulent channel flow by space-dependent electromagnetic force and the mechanism of drag reduction are investigated with the direct numerical simulation (DNS) methods for different Reynolds numbers. A formulation is derived to express the relation between the drag and the Reynolds shear stress. With the application of optimal electromagnetic force, the in-depth relations among characteristic structures in the flow field, mean Reynolds shear stress, and the effect of drag reduction for different Reynolds numbers are discussed. The results indicate that the maximum drag reductions can be obtained with an optimal combination of parameters for each case of different Reynolds numbers. The regular quasi-streamwise vortex structures, which appear in the flow field, have the same period with that of the electromagnetic force. These structures suppress the random velocity fluctuations, which leads to the absolute value of mean Reynolds shear stress decreasing and the distribution of that moving away from the wall. Moreover, the wave number of optimal electromagnetic force increases, and the scale of the regular quasi-streamwise vortex structures decreases as the Reynolds number increases. Therefore, the rate of drag reduction decreases with the increase in the Reynolds number since the scale of the regular quasi-streamwise vortex structures decreases.

Key words: flow control, composite materials, laminated plates, dynamic stability, electromagnetic force, turbulent channel flow, drag reduction

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