Turbulent-viscosity modeling applicable to swirling flows, based on a composite time scale with mean flow helicity partially incorporated
Turbulent-viscosity modeling applicable to swirling flows, based on a composite time scale with mean flow helicity partially incorporated
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适用于旋流的湍流粘度建模，基于部分包含平均流量螺旋的复合时间尺度
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
Y. Matsuo
中科院分区：
文献类型：
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作者：
A. Yoshizawa;H. Abe;H. Fujiwara;Y. Mizobuchi;Y. Matsuo
螺旋运动有助于湍流的稳定，这是通过其平均速度分布来认识的。这一特征表明旋涡能够抑制动量输运。在目前的雷诺平均模拟中，流动被认为超出了以湍流-粘性表示为关键因素的显式代数模拟的范围，而二阶模拟是唯一的方法，代价是增加了数学和计算的复杂性。本文的目的是在各向同性湍流-粘性模型的框架内再现旋流的主要特征，并扩展显式代数模拟的能力。它的基石是引入了一个复合时标，在不违反伽利略不变性的情况下，部分纳入了平均流动螺旋度。将时间尺度与当前模拟中常见的单一时间尺度合成，在此基础上模拟湍流粘性，并将其纳入两方程模拟。在旋转管流中对该模型进行了试验，证实该模型再现了模型的主要特征，表明动量输运受到环向流动的部分平均螺旋度和轴向滞后流的涡度的抑制。
Helical motion contributes to the stabilization of turbulent flows, as is recognized through their mean velocity profiles. This feature indicates that swirl is capable of suppressing momentum transport. In the current Reynolds-averaged modeling, the flow is regarded as beyond the scope of the explicit algebraic modeling with the turbulent-viscosity representation as a key ingredient, and the second-order modeling is utilized as the sole approach at the cost of the increase in mathematical and computational complexity. The present work aims at reproducing primary features of swirling flows within the framework of an isotropic turbulent-viscosity model and extending the ability of the explicit algebraic modeling. Its cornerstone is the introduction of a composite time scale with the mean flow helicity partially incorporated without violating the Galilean invariance. The time scale is synthesized with the single ones familiar in the current modeling, on the basis of which the turbulent viscosity is modeled and incorporated into the two-equation modeling. The model is tested in a swirling pipe flow and is confirmed to reproduce its primary features, showing that the momentum transport is suppressed by the partial mean flow helicity due to the circumferential flow and the vorticity resulting from the retarded axial flow.