Abstract

Predicting the force exerted on an object as it penetrates a granular medium is of interest in engineering, locomotive, and geotechnical applications. Current models of granular drag, however, vary widely in applicability and parameterization, and the physical origin of the granular resistive force itself is a subject of debate. Here we perform constant speed penetration experiments, combined with calibrated, large-scale molecular dynamics simulations, at velocities up to 2 m/s to test the effect of impact velocity on the depth dependent ‘hydrostatic’ drag force. We discover that the evolution of the granular flow field around an intruder regulates the presence of depth dependent drag forces. In addition, we find that the observed linear depth dependence is commensurate with the mass of flowing grains. These results suggest that, as the impact speed increases beyond the quasistatic regime, the depth dependent drag term becomes intertwined with inertial effects.

Graphic abstract

中文翻译：

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恒定速度渗透到颗粒材料中：从准静态到惯性状态的拉力

摘要

在工程，机车和岩土工程应用中，预测物体穿透颗粒介质时施加的力非常重要。但是，当前的颗粒阻力模型在适用性和参数设置方面差异很大，而颗粒阻力的物理来源本身就是一个争论的话题。在这里，我们进行恒速穿透实验，并与经过校准的大规模分子动力学模拟相结合，以高达2 m / s的速度测试冲击速度对取决于深度的“静水力”拖曳力的影响。我们发现入侵者周围的颗粒流场的演变调节了深度依赖的拖曳力的存在。此外，我们发现观察到的线性深度依赖性与流动晶粒的质量相对应。这些结果表明，

图形摘要