Enstrophy cascades in two-dimensional dense granular flows
Enstrophy cascades in two-dimensional dense granular flows
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二维密集颗粒流中的熵级联
DOI：
10.1103/physreve.94.022908
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发表时间：
2016
影响因子：
2.4
通讯作者：
Kuniyasu Saitoh and Hideyuki Mizuno
中科院分区：
文献类型：
--
作者：
Jingxiang Xu;Yuji Higuchi;Nobuki Ozawa;Kazuhisa Sato;Toshiyuki Hashida;Momoji Kubo;Kuniyasu Saitoh and Hideyuki Mizuno
采用二维分子动力学方法模拟致密颗粒材料在简单剪切变形下的涡旋结构。引入涡度场作为衡量局部自旋运动的粒子，我们观察到它们的非均匀分布，其中涡度场的统计表现出高度非高斯的行为和典型的域的涡度场的大小显着增加，如果系统是准静态变形下屈服。在这种稠密的颗粒流中，涡度谱在介观尺度下呈幂律衰减，这意味着动能耗散的局部结构异常。我们解释的幂律衰减，或拟能级联在致密的颗粒状材料，通过量纲分析，涡度谱的依赖不仅对波数，而且对剪切速率，很好地解释。从我们的量纲分析，颗粒温度和转动动能的标度也进行了预测。
Employing two-dimensional molecular dynamics simulations of dense granular materials under simple shear deformations, we investigate vortex structures of particle rearrangements. Introducing vorticity fields as a measure of local spinning motions of the particles, we observe their heterogeneous distributions, where statistics of vorticity fields exhibit the highly non-Gaussian behavior and typical domain sizes of vorticity fields significantly increase if the system is yielding under quasistatic deformations. In such dense granular flows, a power-law decay of vorticity spectra can be observed at mesoscopic scale, implying anomalous local structures of kinetic energy dissipation. We explain the power-law decay, or enstrophy cascades in dense granular materials, by a dimensional analysis, where the dependence of vorticity spectra not only on the wave number, but also on the shear rate, is well explained. From our dimensional analyses, the scaling of granular temperature and rotational kinetic energy is also predicted.