Direct numerical simulation of fractal-generated turbulence
Direct numerical simulation of fractal-generated turbulence
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DOI：
10.1088/0169-5983/45/6/061409
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发表时间：
2013-12-01
影响因子：
1.5
通讯作者：
Ushijima, T.
中科院分区：
文献类型：
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作者：
Suzuki, H.;Nagata, K.;Ushijima, T.
我们模拟分形产生的湍流（赫斯特和Vassilicos 2007物理流体19 035103））通过直接数值模拟，并解决其基本特征。我们检查是否分形产生的湍流在上游区域具有类似的性质的唤醒。我们提出了一个方程，用于预测峰值的速度波动强度，并设计了一种方法，用于制定的功能形式的关注的数量，通过专注于时间尺度上的衰减湍流，我们检查这些形式的湍流动能和均方根的压力波动通过这种方法。通过使用该方法，这两个功能的形式被发现是幂律函数在下游区域，即使这些配置文件遵循这些峰周围的指数函数。此外，这些量的衰减指数估计。横向和流向速度波动的积分长度尺度在下游方向上基本恒定。具有这两个特征的衰减湍流与预测指数衰减的理论所描述的衰减湍流相冲突。我们讨论了一个因素造成的差异，专注于均匀，各向同性湍流的传递函数的函数形式。
We simulate fractal-generated turbulence (Hurst and Vassilicos 2007 Phys. Fluids 19 035103)) by means of a direct numerical simulation and address its fundamental characteristics. We examine whether the fractal-generated turbulence in the upstream region has a nature similar to that of a wake. We propose an equation for predicting peak values of the velocity fluctuation intensity and devise a method for formulating the functional form of the quantity of interest by focusing on the time scale of decaying turbulence, and we examine those forms for the turbulent kinetic energy and rms of pressure fluctuation through this method. By using the method, both of these functional forms are found to be power-law functions in the downstream region, even though these profiles follow exponential functions around these peaks. In addition, decay exponents of these quantities are estimated. The integral length scales of velocity fluctuations for transverse as well as streamwise directions are essentially constant in the downstream direction. Decaying turbulence having both these characteristics conflicts with decaying turbulence described by the theory predicting exponential decay. We discuss a factor causing the difference by focusing on the functional form of the transfer function of homogeneous, isotropic turbulence.