Finger Tilo, Voigt Andreas, Stadler Jörg, Niessen Heiko G, Naji Lama, Stannarius Ralf
Otto-von-Guericke-University, Institute of Experimental Physics, Universitätsplatz 2, D-39106 Magdeburg, Germany.
Phys Rev E Stat Nonlin Soft Matter Phys. 2006 Sep;74(3 Pt 1):031312. doi: 10.1103/PhysRevE.74.031312. Epub 2006 Sep 29.
Segregation structures of granular mixtures in rotating drums represent classical examples of pattern formation in granular material. We investigate the coarsening of axial segregation patterns of slurries in a long horizontally rotating cylinder. The dynamics and the three-dimensional geometry of the segregation structures are analyzed with optical methods and nuclear magnetic resonance imaging. Previous studies have mainly considered global statistical features of the pattern dynamics. In order to get insight into driving mechanisms for the coarsening process, we focus on the details of the dissolution of individual bands. We treat the coarsening as a consequence of interactions of adjacent bands in the pattern, which are determined by their geometrical relations. In addition to initially homogeneous mixtures, which evolve to spontaneously formed patterns, we study the evolution of specially prepared simple initial states. The role of the three-dimensional geometry of the axial core in the dissolution process of segregation bands is demonstrated. Relations between geometry and dynamic processes are established, which may help to find the correct microscopic models for the coarsening mechanism.
旋转鼓中颗粒混合物的分离结构是颗粒材料中模式形成的经典例子。我们研究了长水平旋转圆柱中浆料轴向分离模式的粗化过程。利用光学方法和核磁共振成像分析了分离结构的动力学和三维几何形状。以往的研究主要考虑了模式动力学的全局统计特征。为了深入了解粗化过程的驱动机制，我们关注单个条带溶解的细节。我们将粗化视为模式中相邻条带相互作用的结果，这些相互作用由它们的几何关系决定。除了初始均匀混合物演变为自发形成的模式外，我们还研究了特殊制备的简单初始状态的演化。证明了轴向核心的三维几何形状在分离带溶解过程中的作用。建立了几何形状与动态过程之间的关系，这可能有助于找到粗化机制的正确微观模型。
