Direct numerical simulation of spatially developing turbulent boundary layers with uniform blowing or suction
Direct numerical simulation of spatially developing turbulent boundary layers with uniform blowing or suction
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DOI：
10.1017/jfm.2011.219
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发表时间：
2011-06
影响因子：
3.7
通讯作者：
Y. Kametani;K. Fukagata
中科院分区：
文献类型：
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作者：
Y. Kametani;K. Fukagata
对具有均匀吹气（UB）或均匀吸力（US）的空间发展湍流边界层进行直接数值模拟（DNS），旨在减少表面摩擦阻力。基于自由流速度和入口处 99% 边界层厚度的雷诺数设置为 3000。在范围 -0.01U∞ ≤ Vctr ≤ 0.01U∞ 的壁上应用恒定的壁法向速度。 DNS 结果表明，UB 降低了表面摩擦阻力，而 US 则增加了表面摩擦阻力。湍流波动表现出相反的趋势：UB增强湍流，而US抑制湍流。使用恒等方程（FIK 恒等式）对局部表面摩擦系数 cf 进行动态分解（Fukagata, Iwamoto & Kasagi, Phys. Fluids, vol. 14, 2002, pp. L73–L76）表明，UB 情况下的平均对流项作为强阻力减小因子，而在 US 情况下则作为强阻力增强因子：在这两种情况下，平均对流项对 摩擦阻力压倒了湍流的贡献。研究还发现，UB 的控制效率远高于针对通道流提出的先进主动控制方法。
Direct numerical simulation (DNS) of spatially developing turbulent boundary layer with uniform blowing (UB) or uniform suction (US) is performed aiming at skin friction drag reduction. The Reynolds number based on the free stream velocity and the 99% boundary layer thickness at the inlet is set to be 3000. A constant wall-normal velocity is applied on the wall in the range, −0.01U∞ ≤ Vctr ≤ 0.01U∞. The DNS results show that UB reduces the skin friction drag, while US increases it. The turbulent fluctuations exhibit the opposite trend: UB enhances the turbulence, while US suppresses it. Dynamical decomposition of the local skin friction coefficient cf using the identity equation (FIK identity) (Fukagata, Iwamoto & Kasagi, Phys. Fluids, vol. 14, 2002, pp. L73–L76) reveals that the mean convection term in UB case works as a strong drag reduction factor, while that in US case works as a strong drag augmentation factor: in both cases, the contribution of mean convection on the friction drag overwhelms the turbulent contribution. It is also found that the control efficiency of UB is much higher than that of the advanced active control methods proposed for channel flows.