CAREER: Liquid-drop impacts on granular surfaces and the universality in granular impact cratering

非技术摘要我们所有看过雨滴在后院或海滩上飞溅的人都可能对液滴造成的颗粒撞击陨石坑很熟悉。这种普遍存在的现象与许多重要的自然、农业和工业过程直接相关，如土壤侵蚀、滴灌、微生物在土壤中的扩散以及颗粒和粉末的喷洒。更令人惊讶的是，液滴的颗粒状撞击陨石坑和小行星撞击行星体的陨石坑在能量标度和撞击坑形状方面显示出数量上相似的特征。本课题研究了撞击液滴和撞击颗粒在撞击过程中的快速动力学，并利用这些动力学模型建立了描述颗粒介质中雨滴印迹形态的定量模型。该项目还旨在揭示颗粒撞击陨石坑的普遍特征，并寻找不同颗粒撞击陨石坑过程之间的联系，包括实心球体撞击陨石坑、液滴撞击陨石坑、小行星撞击陨石坑和爆炸陨石坑。为了探索快速撞击动力学，参与该项目的学生接受了最先进的高速和辐射成像技术的培训。该项目可以为环境保护和工业中涉及液滴撞击颗粒表面的各种活动提供实用指导。技术摘要与软物质研究中的两个长期存在的问题，即液滴对固体/液体表面的撞击和固体球体对颗粒的撞击，液滴对颗粒表面的撞击是出了名的复杂。该项目的目标是研究液滴撞击颗粒表面的动力学，并探索颗粒撞击在不同能量尺度上形成凹坑的普遍特征。这项研究将高速摄影与先进的放射成像技术相结合，旨在揭示颗粒介质中液滴撞击的详细动力学，并为预测液滴撞击事件的结果提供一个定量模型。研究中发展的实验技术和物理见解对于解决在更广泛的背景下研究液滴撞击动力学和颗粒撞击凹坑所面临的困难问题相当有用。此外，这项研究有助于阐明颗粒状撞击陨石坑的普遍特征，并可能为探索与小行星撞击相关的高能颗粒状撞击陨石坑开辟一条新途径。这项研究还可能有助于土壤侵蚀的土壤科学研究、小行星撞击的天体物理研究和原始降雨活动的地质研究。

Non-Technical AbstractGranular impact cratering by liquid drops is likely familiar to all of us who have watched raindrops splashing in a backyard or on a beach. Such a ubiquitous phenomenon is directly relevant to many important natural, agricultural and industrial processes such as soil erosion, drip irrigation, dispersion of micro-organisms in soil, and spray-coating of particles and powders. It is even more surprising that granular impact cratering by liquid drops and asteroid impact cratering on planetary bodies show quantitatively similar features in terms of the energy scaling and the shape of impact craters. The present project investigates the fast dynamics of impinging liquid drops and impacted granular particles during impact events, which are then used to develop a quantitative model for describing the morphology of raindrop imprints in granular media. The project also aims to reveal universal features of granular impact cratering and search the link between different granular cratering processes including solid-sphere impact cratering, liquid-drop impact cratering, asteroid impact cratering and explosion cratering. To probe the fast impact dynamics, students working on the project are trained in the state-of-the-art high-speed and radiological imaging techniques. The project can provide practical guides to various activities in environmental protection and industry involving liquid-drop impacts on granular surfaces.Technical AbstractDirectly related to two long-standing problems in soft matter research, i.e., drop impact on solid/liquid surfaces and granular impact cratering by solid spheres, liquid drop impact on granular surfaces is notoriously complicated. The objective of the project is to investigate the dynamics of liquid-drop impact on granular surfaces and explore universal features of granular impact cratering across widely different energy scales. Combining high-speed photography with advanced radiological imaging techniques, the study aims to uncover the detailed dynamics of liquid-drop impact in granular media and provide a quantitative model for predicting of the outcome of liquid-drop impact events. The experimental techniques and physical insights developed in the research are considerably useful for solving difficult problems faced in the study of drop impact dynamics and granular impact cratering in much broader contexts. Moreover, the study helps to illustrate universal features in granular impact cratering and may open up a new way to probe high-energy granular impact cratering associated with asteroid strikes. The study can also potentially benefit soil science research on soil erosion, astrophysical research on asteroid strikes and geological research on primordial rain activities.