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arXiv 1803.06009cond-mat.soft
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非晶塑性介观晶格模型中的扩散

Diffusion in mesoscopic lattice models of amorphous plasticity

Botond Tyukodi, Craig E Maloney, Damien Vandembroucq

摘要:

我们提出了在非热准静态条件下的剪切非晶材料的介观晶格模型中的标记粒子扩散的结果。我们发现一个短时间扩散制度和一个长时间扩散制度的扩散系数依赖于系统的大小在显着不同的方式。在短时间内,我们发现扩散系数$D$与系统长度$D\sim L^{1.05}$大致呈线性关系。这种短时间行为与基于粒子的模拟一致。长时间扩散系数的尺度类似于$D\sim L^{1.6}$,接近于发现$D\sim L^{1.5}$的先前研究。此外,我们表明,近场的相互作用内核的细节不影响短时间的行为,但定性和显着影响的长时间的行为,可能会导致饱和的均方位移在很长的时间。我们发现的一个$D\sim L^{1.05}$短时间缩放解决了一个长期存在的难题之间的分歧,在颗粒为基础的模型和介观尺度晶格模型的非晶塑性扩散系数测量。

英文摘要:

We present results on tagged particle diffusion in a meso-scale lattice model for sheared amorphous material in athermal quasi-static conditions. We find a short time diffusive regime and a long time diffusive regime whose diffusion coefficients depend on system size in dramatically different ways. At short time, we find that the diffusion coefficient, $D$, scales roughly linearly with system length, $D\sim L^{1.05}$. This short time behavior is consistent with particle-based simulations. The long-time diffusion coefficient scales like $D\sim L^{1.6}$, close to previous studies which found $D\sim L^{1.5}$. Furthermore, we show that the near-field details of the interaction kernel do not affect the short time behavior, but qualitatively and dramatically affect the long time behavior, potentially causing a saturation of the mean-squared displacement at long times. Our finding of a $D\sim L^{1.05}$ short time scaling resolves a long standing puzzle about the disagreement between the diffusion coefficient measured in particle-based models and meso-scale lattice models of amorphous plasticity.

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