Peculiarities in breakup and transport process of shock-induced ejecta with surrounding gas

Abstract

The interaction of shock-induced ejecta with gas beyond the free surface is a critical unsolved issue and being investigated broadly. Using models containing micrometer-sized gas environments, we perform molecular dynamics simulations to investigate the coupling interactions of surrounding gases with ejecta from shock-loaded tin surface. Ejected microjets experience progressively aggravated deceleration with increasing gas density, and particle flows ahead of jet tips are suppressed. Despite the drag effect, the primary fragmentation process is yet intrinsically dominated by a velocity gradient. The continuous interaction between ejecta and gas leads to the progressive formation of transmitted shock waves in background gases, which is jointly determined by ejecta velocity and thermophysical properties of gas. Meanwhile, a mixing layer between ejecta and gas is directly observed, leading to discrepant mass distributions of ejecta along shock direction. With increasing gas density, the volume density tends to rise in the mixing zone while the zone thickness decreases. Further, with the presence of gases, the size distribution of ejected particles is altered with an outstanding feature of enhanced formation of atomic particles. It is found that the stripping effect of gas dominates the growth of ejecta clusters in the transport process. The stripped particles strongly couple and flow with compressed gas, accompanied by recombination into subsequent clusters. As the gas density increases, both formation and annihilation of atomic particles are promoted. The revealed peculiarities provide microscopic views of ejecta interaction with ambient gas, which would further the understanding of gas effects on the breakup and transport of ejected particles.

Dynamics behavior of porous tin under strong shockwave impact

“…强冲击作用下的金属材料动态破碎过程, 既包含 简单的单次加载微喷、层裂/微层裂破碎 [1][2][3][4][5][6][7][8][9][10][11][12][13] , 也有复 杂多次加载产生的表面微射流、主体区域反复冲击再 破碎、主体区域对微射流颗粒回收等一系列复杂过 程 [14][15][16] , 是耦合材料特性、加载状态、样品初始状态 等多因素的复杂多尺度问题, 在惯性约束核聚变、冲 击防护等领域有重要的工程价值和科学意义, 最近几 十年被广泛研究 [17][18][19] .…”

An improved model of damage depth of shock-melted metal in microspall under triangular wave loading*

“…On the other hand, the damage depth is closely related to the physical processes such as secondary shock and particle-gas mixing. [20][21][22] Shao et al [23] proposed an approximate description of damage depth under triangular wave loading when the material's compressibility is considered. However, under strong triangular wave loading, the effect of the relative movement is obvious and should also be taken into account when performing theoretical modeling of damage depth.…”

Microjet formation from the grooved surface of aluminum under shock waves with different pulse durations

“…Theoretically, Piriz et al [23] proposed an analytical model based on the linear Richtmyer-Meshkov instability (RMI) in solids under the conditions of high-energy-density, and showed that plasticity determined the maximum perturbation amplitude and provides simple scaling laws. Besides, molecular dynamics (MD) [1,12,24,25], Eulerian [14,26,27], and smoothed particle hydrodynamics (SPH) [28][29][30] methods have all been used to simulate the microjet formation. Dimonte et al [31] described a simple algebraic model for the microjet based on the hydrodynamics and MD simulations of the RMI.…”