We study experimentally the formation of a dual hierarchical jetting pattern in dry dense particle media subjected to the radially divergent shock loadings in a radial Hele-Shaw cell. The distinct internal and external jetting patterns were formed on the internal and external surfaces of a ring at different times, respectively. The former features dozens of radially aligned fine filaments. By contrast, the latter consists of a large number of small spikes. Once the internal jets are fully developed, a novel proportionate growth is observed, in which distinguishable structures of the overall pattern all grow at the same rate until the interaction between the internal and external jets becomes significant, leading to the inversion of the internal jetting pattern. Although the external jetting is found to be an instability of a Rayleigh–Taylor (RT) type, the internal jetting exhibits a much delayed onset and slower early-stage growth compared with the RT instability, indicating different underlying physics.

中文翻译：

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径向爆炸的粒子环的双重分层粒子喷射

我们通过实验研究了在径向Hele-Shaw单元中承受径向发散冲击载荷的干燥致密颗粒介质中双重分层喷射模式的形成。分别在不同的时间在环的内表面和外表面上形成不同的内部和外部喷射图案。前者具有数十根径向排列的细丝。相反，后者由大量的小尖峰组成。一旦内部射流充分发育，就会观察到新的成比例增长，其中整体模式的可分辨结构都以相同的速率增长，直到内部和外部射流之间的相互作用变得显着，从而导致内部射流模式反转。