Structure functions and applicability of Yaglom's relation in passive-scalar turbulent mixing at low Schmidt numbers with uniform mean gradient
Structure functions and applicability of Yaglom's relation in passive-scalar turbulent mixing at low Schmidt numbers with uniform mean gradient
复制标题
均匀平均梯度低施密特数被动标量湍流混合中 Yaglom 关系的结构函数和适用性
DOI：
10.1063/1.4892581
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发表时间：
2014
影响因子：
4.6
通讯作者：
P. Yeung
中科院分区：
文献类型：
--
作者：
K. Iyer;P. Yeung
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An extensive direct numerical simulation database over a wide range of Reynolds and Schmidt numbers is used to examine the Schmidt number dependence of the structure function of passive scalars and the applicability of the so-called Yaglom's relation in isotropic turbulence with a uniform mean scalar gradient. For the moderate Reynolds numbers available, the limited range of scales in scalar fields of very low Schmidt numbers (as low as 1/2048) is seen to lead to weaker intermittency, and weaker alignment between velocity gradients and principal strain rates. Strong departures from both Obukhov-Corrsin scaling for second-order structure functions and Yaglom's relation for the mixed velocity-scalar third-order structure function are observed. Evaluation of different terms in the scalar structure function budget equation assuming statistical stationarity in time shows that, if the Schmidt number is very low, at intermediate scales production and diffusion terms (instead of advection) are major contributors in the balance against dissipation.