Suboptimal feedback control of turbulent flow over a backward-facing step

被引:41
作者
Kang, SW
Choi, H [1 ]
机构
[1] Seoul Natl Univ, Sch Mech & Aerosp Engn, Seoul 151742, South Korea
[2] Seoul Natl Univ, Natl CRI Ctr Turbulence & Flow Control Res, Inst Adv Machinery & Design, Seoul 151742, South Korea
关键词
D O I
10.1017/S0022112002008728
中图分类号
O3 [力学];
学科分类号
08 ; 0801 ;
摘要
The objective of the present numerical study is to increase mixing in turbulent flow behind a backward-facing step using a systematic feedback control method. Spatially and temporally varying blowing and suction with zero-net mass flow rate are provided at the step edge, based on the sensing of the spanwise distribution of the wall pressure fluctuations at a downstream location. The cost functional to be increased is the root-mean-square spanwise pressure-gradient fluctuations at the sensing location, which may be associated with mixing behind the backward-facing step. Given the cost functional, the actuation at the step edge is determined through the suboptimal feedback control procedure of Choi et al. (1993). Large-eddy simulations of turbulent flow are conducted at a Reynolds number of 5100 based on the step height and free-stream velocity. The results of suboptimal feedback controls are compared with those of non-feedback single-frequency actuations. In case of the suboptimal control, velocity and vorticity fluctuations substantially increase downstream of the backward-facing step as well as in the recirculation zone. As a result, the reattachment length is significantly reduced, as compared to those of uncontrolled flow and flow with single-frequency actuations. A simple open-loop control method is devised from the suboptimal feedback control result, producing nearly the same mixing enhancement as the feedback control.
引用
收藏
页码:201 / 227
页数:27
相关论文
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