Wyser Emmanuel, Carrea Dario, Jaboyedoff Michel, Pudasaini Shiva P
University of Lausanne, Institute of Earth Sciences, Lausanne, Switzerland.
University of Bonn, Institute of Geosciences, Geophysics Section, Bonn, Germany.
Eur Phys J E Soft Matter. 2019 Aug 28;42(8):111. doi: 10.1140/epje/i2019-11877-8.
This experimental work focuses on the cratering response of granular layers induced by liquid droplet impacts. A droplet impact results in severe granular layer deformation, crater formation and deposits in the vicinity of the impact center. High-precision three-dimensional imaging of the granular layer surface revealed important characteristics of liquid impacts on granular matter, such as singular asymmetric deformations of the layer. Our analysis also demonstrated that the impact energy and the granular packing, and its inherent compressibility, are not the unique parameters controlling the bed response, for which granular fraction heterogeneities may induce strong variations. Such heterogeneous conditions primarily influence the magnitude but not the dynamics of liquid impacts on granular layers. Finally, a general equation can be used to relate the enery released during cratering to both the impact energy and the compressibility of the granular matter. However, our results do not support any transition triggered by the compaction-dilation regime. Hence, higly detailed numerical simulations could provide considerable insights regarding the remaining questions related to heterogeneous packing conditions and its influence over the bulk compressibility and the compaction-dilation phase transition.
这项实验工作聚焦于液滴冲击引起的颗粒层坑洼响应。液滴冲击会导致颗粒层严重变形、形成坑洼以及在冲击中心附近产生沉积物。对颗粒层表面的高精度三维成像揭示了液体对颗粒物质冲击的重要特征，例如该层的奇异不对称变形。我们的分析还表明，冲击能量、颗粒堆积及其固有压缩性并非控制床层响应的唯一参数，颗粒级分的不均匀性可能会导致强烈变化。这种不均匀条件主要影响液体对颗粒层冲击的幅度而非动力学。最后，一个通用方程可用于将坑洼形成过程中释放的能量与冲击能量和颗粒物质的压缩性联系起来。然而，我们的结果并不支持由压实 - 膨胀机制引发的任何转变。因此，高度详细的数值模拟可以为与不均匀堆积条件及其对整体压缩性和压实 - 膨胀相变的影响相关的剩余问题提供相当多的见解。
