【摘要】 利用直接数值模拟研究了带有壁面展向周期振动的槽道湍流.壁面在展向的周期运动使湍流受到抑制,并使壁面摩擦阻力减小.通过对雷诺应力输运方程的分析研究了壁面展向周期振动的减阻机理,进一步揭示了压力变形项在湍流抑制中的关键作用.更多还原

【Abstract】 An investigation into a turbulent channel flow subjected to spanwise wall oscillation is carried out via direct numerical simulation. By wall oscillation, turbulence is suppressed and friction drag is reduced. The transportation of Reynolds stresses under the influence of the oscillating wall is analyzed at the initial and statistically stationary stages to further disclose the mechanism of turbulence suppression and drag reduction. It is found that the moving wall can cause the transient growth of spanwise velocity fluctuations only at the very beginning of wall oscillation and thereafter the pressure-strain terms play an important role. The attenuation of turbulence intensities and skin friction at the statistically stationary stage is mainly due to the sustained reduction of the pressure-strain terms.更多还原