Morphodynamics of a dense particulate medium under radial explosion
Morphodynamics of a dense particulate medium under radial explosion
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径向爆炸下致密颗粒介质的形态动力学
DOI：
10.1039/c9sm02150g
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发表时间：
2020
期刊：
影响因子：
3.4
通讯作者：
Bai Chunhua
中科院分区：
文献类型：
--
作者：
Xue Kun;Han Panpan;Du Kaiyuan;Gan Yixiang;Wang Ziwei;Bai Chunhua
在本文中，我们调查的不稳定图案的起始和增长所产生的冲击加载内表面的颗粒环限制在一个Hele-Shaw细胞使用实验和数值方法。在由具有不同形态的颗粒组成的颗粒介质中形成各种图案。当颗粒形状变得越来越不规则，和/或Hele-Shaw晶胞中的差距变得越来越窄时，受限颗粒越来越难以扩散。因此，出现的模式过渡从一个光滑的圆形与平凡的波动，增长在一个自相似的方式，以一个不稳定的指状结构与显着的尖端分裂。明确定义的不稳定模式的独特的增长模式是密切相关的，其起始阶段旁边的传输压实前。初始扰动的失控增长导致了后期指状不稳定性的不稳定增长。相反，初始阶段扰动的最小增长保证了随后的不稳定模式的自相似增长，其特征是微不足道的扰动。颗粒尺度模拟揭示了颗粒介质固有的非均匀非线性力网络在不稳定模式从稳定到不稳定的转变中所起的基本作用。目前的工作揭示了冲击加载粒状介质和所产生的宏观尺度不稳定模式的性质形成的表面不稳定性的颗粒尺度物理之间的相关性。通过有限空间的宏观流动性的颗粒被认为是最重要的指标的冲击引起的颗粒不稳定性模式的性质。
In this paper, we investigate the initiation and growth of instability patterns arising from the shock loaded internal surfaces of granular rings confined in a Hele-Shaw cell using both experimental and numerical approaches. A variety of patterns are formed in granular media consisting of grains with varying morphologies. When the particle shape becomes increasingly irregular, and/or the gap in the Hele-Shaw cell becomes narrower, it is increasingly hard for confined particles to fluidize. Consequently the emergent pattern transitions from a smooth circle with trivial undulation which grows in a self-similar manner to an unstable finger-like structure with significant tip-splitting. The distinct growth mode of the well-defined instability pattern is closely associated with its inception phase alongside the transmission of the compaction front. The runaway growth of the incipient perturbations gives rise to the unstable growth of the late-time finger-like instabilities. Conversely the minimal growth of the perturbations in the inception phase guarantees the ensuing self-similar growth of the instability patterns featuring insignificant corrugation. The grain-scale simulations reveal the fundamental role played by the heterogeneous non-linear force network inherent to granular media in the stable-to-unstable transition of the instability pattern. The present work reveals the correlation between the grain-scale physics underpinning the formation of surface instability upon shock loading granular media and the nature of the resulting macro-scale instability patterns. The macroscopic flowability of particles through the confined space is found to be the foremost indicator of the nature of the shock induced granular instability pattern.