Applied Mathematics and Mechanics (English Edition) ›› 2019, Vol. 40 ›› Issue (7): 1041-1052.doi: https://doi.org/10.1007/s10483-019-2500-8

• 论文 • 上一篇    

Drag reduction of turbulent channel flows over an anisotropic porous wall with reduced spanwise permeability

Qingxiang LI1, Ming PAN1, Quan ZHOU1,2, Yuhong DONG1,2   

  1. 1. Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai 200072, China;
    2. Shanghai Key Laboratory of Mechanics in Energy Engineering, Shanghai University, Shanghai 200072, China
  • 收稿日期:2018-06-12 修回日期:2018-12-12 出版日期:2019-07-01 发布日期:2019-07-01
  • 通讯作者: Yuhong DONG E-mail:dongyh@staff.shu.edu.cn
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Nos. 11572183, 91852111, and 11825204) and the Program of Shanghai Municipal Education Commission (No. 2019-01-07-00-09-E00018)

Drag reduction of turbulent channel flows over an anisotropic porous wall with reduced spanwise permeability

Qingxiang LI1, Ming PAN1, Quan ZHOU1,2, Yuhong DONG1,2   

  1. 1. Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai 200072, China;
    2. Shanghai Key Laboratory of Mechanics in Energy Engineering, Shanghai University, Shanghai 200072, China
  • Received:2018-06-12 Revised:2018-12-12 Online:2019-07-01 Published:2019-07-01
  • Contact: Yuhong DONG E-mail:dongyh@staff.shu.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Nos. 11572183, 91852111, and 11825204) and the Program of Shanghai Municipal Education Commission (No. 2019-01-07-00-09-E00018)

摘要: The direct numerical simulation (DNS) is carried out for the incompressible viscous turbulent flows over an anisotropic porous wall. Effects of the anisotropic porous wall on turbulence modifications as well as on the turbulent drag reduction are investigated. The simulation is carried out at a friction Reynolds number of 180, which is based on the averaged friction velocity at the interface between the porous medium and the clear fluid domain. The depth of the porous layer ranges from 0.9 to 54 viscous units. The permeability in the spanwise direction is set to be lower than the other directions in the present simulation. The maximum drag reduction obtained is about 15.3% which occurs for a depth of 9 viscous units. The increasing of drag is addressed when the depth of the porous layer is more than 25 wall units. The thinner porous layer restricts the spanwise extension of the streamwise vortices which suppresses the bursting events near the wall. However, for the thicker porous layer, the wall-normal fluctuations are enhanced due to the weakening of the wall-blocking effect which can trigger strong turbulent structures near the wall.

关键词: torsion of cracked cylinder, singular integral equations, boundary element method, stress intensity factor, direct numerical simulation (DNS), drag reduction, anisotropic porous medium, turbulent open channel flow

Abstract: The direct numerical simulation (DNS) is carried out for the incompressible viscous turbulent flows over an anisotropic porous wall. Effects of the anisotropic porous wall on turbulence modifications as well as on the turbulent drag reduction are investigated. The simulation is carried out at a friction Reynolds number of 180, which is based on the averaged friction velocity at the interface between the porous medium and the clear fluid domain. The depth of the porous layer ranges from 0.9 to 54 viscous units. The permeability in the spanwise direction is set to be lower than the other directions in the present simulation. The maximum drag reduction obtained is about 15.3% which occurs for a depth of 9 viscous units. The increasing of drag is addressed when the depth of the porous layer is more than 25 wall units. The thinner porous layer restricts the spanwise extension of the streamwise vortices which suppresses the bursting events near the wall. However, for the thicker porous layer, the wall-normal fluctuations are enhanced due to the weakening of the wall-blocking effect which can trigger strong turbulent structures near the wall.

Key words: torsion of cracked cylinder, singular integral equations, boundary element method, stress intensity factor, drag reduction, anisotropic porous medium, direct numerical simulation (DNS), turbulent open channel flow

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