Large-Scale Streamwise Vortices in Turbulent Channel Flow Induced by Active Wall Actuations

作者：Ni, Weidan; Lu, Lipeng; Fang, Jian^*; Moulinec, Charles; Yao, Yufeng

来源：Flow, Turbulence and Combustion, 2018, 100(3): 651-673.

DOI：10.1007/s10494-017-9871-5

• SADS control
• IPC/OPC
• Channel flow
• DNS

Direct numerical simulations of turbulent flow in a plane channel using spanwise alternatively distributed strips (SADS) are performed to investigate the characteristics of large-scale streamwise vortices (LSSVs) induced by small-scale active wall actuations, and their role in suppressing flow separation. SADS control is obtained by alternatively applying out-of-phase control (OPC) and in-phase control (IPC) to the wall-normal velocity component of the lower channel wall, in the spanwise direction. Besides the non-controlled channel flow simulated as a reference, four controlled cases with 1, 2, 3 and 4 pairs of OPC/IPC strips are studied at M = 0.2 and R e = 6,000, based on the bulk velocity and the channel half height. The case with 2 pairs of strips, whose width is Delta z (+) = 264 based on the friction velocity of the non-controlled case, is the most effective in terms of generating large-scale motions. It is also found that the OPC (resp. IPC) strips suppress (resp. enhance) the coherent structures and that leads to the creation of a vertical shear layer, which is responsible for the LSSVs presence. They are in a statistically steady state and their cores are located between two neighbouring OPC and IPC strips. These motions contribute significantly to the momentum transport in the wall-normal and spanwise directions showing potential for flow separation suppression.

• 出版日期2018-4
• 单位北京航空航天大学