Scaling of oblique impacts in frictional targets: Implications for crater size and formation mechanisms
Scaling of oblique impacts in frictional targets: Implications for crater size and formation mechanisms
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DOI：
10.1016/j.icarus.2009.07.018
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发表时间：
2009-12-01
期刊：
影响因子：
3.2
通讯作者：
Collins, Gareth S.
中科院分区：
文献类型：
--
作者：
Elbeshausen, Dirk;Wuennemann, Kai;Collins, Gareth S.
几乎每一次陨石撞击都是以倾斜的角度发生的，但人们对撞击角度对陨石坑大小或形成机制的影响知之甚少。这在很大程度上是由于难以从对自然陨石坑的观测中推断撞击物的性质，如大小、速度和轨迹，以及使用数值模型模拟斜撞击的费用和复杂性。实验室斜撞击实验和以前的数值模型表明，在弹坑挖掘所涉及的部分弹丸的动能显着减少与影响角度。然而，一个彻底的量化行星规模的斜撞击坑并不存在和影响的角度对陨石坑的大小不考虑目前的比例尺。为了解决这一理解上的差距，我们开发了iSALE-3D，这是一种三维多流变流体代码，它足够有效，可以在合理的时间内进行大量高分辨率的斜撞击模拟。在这里，我们提出了一个全面的数值研究的结果，包含200多个三维Hydrocode模拟涵盖了广泛的弹丸尺寸。冲击角和摩擦系数。我们表明，现有的比例定律原则上描述倾斜的行星尺度的影响事件的角度大于30度测量水平。弹坑的位移质量随撞击角度呈正弦曲线下降。然而，我们的研究结果表明，假设弹坑的大小尺度与垂直分量的冲击速度不成立的材料的摩擦系数显着低于0.7（砂）。我们发现，摩擦系数的增加会导致陨石坑变小，陨石坑的形成过程更多地受到撞击物动量的控制，而不是能量的控制。(C)2009 Elsevier Inc. All rights reserved.
Almost every meteorite impact occurs at an oblique angle of incidence, yet the effect of impact angle on crater size or formation mechanism is only poorly understood. This is, in large part, due to the difficulty of inferring impactor properties, such as size, velocity and trajectory, from observations of natural craters, and the expense and complexity of simulating oblique impacts using numerical models. Laboratory oblique impact experiments and previous numerical models have shown that the portion of the projectile's kinetic energy that is involved in crater excavation decreases significantly with impact angle. However, a thorough quantification of planetary-scale oblique impact cratering does not exist and the effect of impact angle on crater size is not considered by current scaling laws. To address this gap in understanding, we developed iSALE-3D, a three-dimensional multi-rheology hydrocode, which is efficient enough to perform a large number of well-resolved oblique impact simulations within a reasonable time. Here we present the results of a comprehensive numerical study containing more than 200 three-dimensional hydrocode-simulations covering a broad range of projectile sizes. impact angles and friction coefficients. We show that existing scaling laws in principle describe oblique planetary-scale impact events at angles greater than 30 degrees measured from horizontal. The displaced mass of a crater decreases with impact angle in a sinusoidal manner. However, our results indicate that the assumption that crater size scales with the vertical component of the impact velocity does not hold for materials with a friction coefficient significantly lower than 0.7 (sand). We found that increasing coefficients of friction result in smaller craters and a formation process more controlled by impactor momentum than by energy. (C) 2009 Elsevier Inc. All rights reserved.