Zhang Qianyun, Gao Ming, Zhao Runchen, Cheng Xiang
Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2015 Oct;92(4):042205. doi: 10.1103/PhysRevE.92.042205. Epub 2015 Oct 26.
Combining high-speed photography with laser profilometry, we study the dynamics and the morphology of liquid-drop impact cratering in wet granular media-a ubiquitous phenomenon relevant to many important geological, agricultural, and industrial processes. By systematically investigating important variables such as impact energy, the size of impinging drops, and the degree of liquid saturation in granular beds, we uncover a scaling law for the size of impact craters. We show that this scaling can be explained by considering the balance between the inertia of impinging drops and the strength of impacted surface. Such a theoretical understanding confirms that the unique energy partition originally proposed for liquid-drop impact cratering in dry granular media also applies for impact cratering in wet granular media. Moreover, we demonstrate that compressive stresses, instead of shear stresses, control the process of granular impact cratering. Our study enriches the picture of generic granular impact cratering and sheds light on the familiar phenomena of raindrop impacts in granular media.
通过将高速摄影与激光轮廓测量技术相结合，我们研究了湿颗粒介质中液滴撞击坑形成的动力学和形态——这是一种普遍存在的现象，与许多重要的地质、农业和工业过程相关。通过系统地研究诸如撞击能量、撞击液滴的大小以及颗粒床层的液体饱和度等重要变量，我们发现了撞击坑大小的标度律。我们表明，这种标度可以通过考虑撞击液滴的惯性与被撞击表面的强度之间的平衡来解释。这样的理论理解证实了最初为干颗粒介质中液滴撞击坑形成所提出的独特能量分配也适用于湿颗粒介质中的撞击坑形成。此外，我们证明了压缩应力而非剪切应力控制着颗粒撞击坑形成的过程。我们的研究丰富了一般颗粒撞击坑形成的图景，并为颗粒介质中雨滴撞击这一常见现象提供了新的见解。
