Drag reduction of compressible wall turbulence with active dimples
Direct numerical simulations are carried out to assess the potential drag reduction of compressible turbulent flow between isothermal walls. For the sake of achieving drag reduction, the flow is actively controlled by deformable dimples lying on the bottom wall of the channel. The first stage of the procedure consists in assessing the optimum geometry of the dimples. In this regard, the lower wall is allowed to freely deform itself according to the loop of control. This method is called the smart wall approach in this paper. By an analysis of the typical shape of the wall deformation thus obtained, it is found that dimples should be thinner than or comparable to the width of streaky structures in the spanwise direction and elongated in the streamwise direction. With active dimples as the walldeformation actuators, a 159c drag reduction is obtained for the flow at Mam = 0.35 while the drag reduction rate is about 12％ for the flow at Mam = 1.5. The fundamental mechanism of the drag reduction is then discussed in this paper. The drag reduction is believed to result from two aspects: the reduction of the mean streamwise velocity gradient near the deformable wall and the suppression of the turbulent fluctuations.
compressible wall turbulence direct numerical simulation active dimples drag reduction
SUN ZhenSheng REN YuXin LARRICQ Cedric
Department of Engineering Mechanics. Tsinghua University, Beijing 100084,China Xiwt Research Instit Department of Engineering Mechanics. Tsinghua University, Beijing 100084,China Department of Engineering Mechanics, Tsinghua University, Beijing 100084,China
国际会议
北京
英文
329-337
2010-04-27（万方平台首次上网日期，不代表论文的发表时间）