Turbulent boundary layers absent mean shear
Turbulent boundary layers absent mean shear
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没有平均剪切的湍流边界层
DOI：
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发表时间：
2011
影响因子：
3.7
通讯作者：
E. Cowen
中科院分区：
文献类型：
--
作者：
B. Johnson;E. Cowen
我们进行了一项实验研究，以调查湍流边界层以上的固定固体玻璃床在平均剪切的情况下。高雷诺数$（Re_{unicode[STIX]{x1 D 706}}sim 300）$通过随机驱动的合成射流阵列产生水平均匀各向同性湍流（RASJA - Variano & Cowen J. Fluid Mech. vol. 604，2008，pp.第1-32段）。每个阵列由时空变化算法控制，这反过来又最大限度地减少了二次平均流的形成。一个数组由一个$8 imes 8$网格的喷气机，而另一个是16美元 imes 16$ array.本文利用粒子图像测速技术研究了各向同性湍流区和湍流遇到静止壁面时形成的边界层。流动的特征在于统计指标，包括平均流量和湍流速度，湍流动能，积分尺度和湍流动能输运方程，其中包括能量耗散率，生产和湍流输运。Tennekes中的经验常数（J. Fluid Mech.第67卷，1975年，第100页）561-567）模型的欧拉频谱计算的基础上耗散的结果和时间频谱的声学多普勒测速测量。我们将我们的结果与先前的文献进行比较，这些文献通过网格搅拌槽实验，移动床实验，快速畸变理论和在强制湍流箱中的直接数值模拟来描述平均剪切自由湍流边界层特性。通过改变随机驱动的合成射流阵列的操作参数，我们还发现，我们能够控制的湍流水平，包括积分长度尺度和耗散率，通过改变平均时间在射流算法。
We perform an experimental study to investigate the turbulent boundary layer above a stationary solid glass bed in the absence of mean shear. High Reynolds number $(Re_{unicode[STIX]{x1D706}}sim 300)$ horizontally homogeneous isotropic turbulence is generated via randomly actuated synthetic jet arrays (RASJA – Variano & Cowen J. Fluid Mech. vol. 604, 2008, pp. 1–32). Each of the arrays is controlled by a spatio-temporally varying algorithm, which in turn minimizes the formation of secondary mean flows. One array consists of an $8 imes 8$ grid of jets, while the other is a $16 imes 16$ array. Particle image velocimetry measurements are used to study the isotropic turbulent region and the boundary layer formed beneath as the turbulence encounters a stationary wall. The flow is characterized with statistical metrics including the mean flow and turbulent velocities, turbulent kinetic energy, integral scales and the turbulent kinetic energy transport equation, which includes the energy dissipation rate, production and turbulent transport. The empirical constant in the Tennekes (J. Fluid Mech. vol. 67, 1975, pp. 561–567) model of Eulerian frequency spectra is calculated based on the dissipation results and temporal frequency spectra from acoustic Doppler velocimetry measurements. We compare our results to prior literature that addresses mean shear free turbulent boundary layer characterizations via grid-stirred tank experiments, moving-bed experiments, rapid-distortion theory and direct numerical simulations in a forced turbulent box. By varying the operational parameters of the randomly actuated synthetic jet array, we also find that we are able to control the turbulence levels, including integral length scales and dissipation rates, by changing the mean on-times in the jet algorithm.
各向同性湍流引起的跨严重污染水面的传质
影响因子：
3.7
作者：
Herlina;Wissink
通讯作者：
Wissink