Börzsönyi Tamás, Ecke Robert E, McElwaine Jim N
Research Institute for Solid State Physics and Optics, Post Office Box 49, H-1525 Budapest, Hungary.
Phys Rev Lett. 2009 Oct 23;103(17):178302. doi: 10.1103/PhysRevLett.103.178302.
Dense granular flows are often unstable and form inhomogeneous structures. Although significant advances have been recently made in understanding simple flows, instabilities of such flows are often not understood. We present experimental and numerical results that show the formation of longitudinal stripes that arise from instability of the uniform flowing state of granular media on a rough inclined plane. The form of the stripes depends critically on the mean density of the flow with a robust form of stripes at high density that consists of fast sliding pluglike regions (stripes) on top of highly agitated boiling material--a configuration reminiscent of the Leidenfrost effect when a droplet of liquid lifted by its vapor is hovering above a hot surface.
密集颗粒流通常是不稳定的，会形成不均匀的结构。尽管最近在理解简单颗粒流方面取得了重大进展，但此类颗粒流的不稳定性往往仍不为人所理解。我们给出的实验和数值结果表明，在粗糙斜面上，颗粒介质均匀流动状态的不稳定性会导致纵向条纹的形成。条纹的形态严重依赖于颗粒流的平均密度，在高密度情况下会形成一种稳定的条纹形态，由快速滑动的块状区域（条纹）叠加在剧烈搅动的沸腾物质之上构成，这种结构让人联想到莱顿弗罗斯特效应，即液滴被其蒸汽托起并悬浮在热表面上方的现象。
