Size Segregation and Convection of Granular Mixtures Almost Completely Packed in the Rotating Thin Box

Size segregation of granular mixtures which are almost completely packed in a rotating drum is discussed with an effective simulation and a brief analysis. Instead of a 3D drum, we simulate 2D rotating thin box which is almost completely packed with granular mixtures. The phase inversion of radially segregated pattern which was found in a 3D experiment are qualitatively reproduced with this simulation, and a brief analysis is followed. Moreover in our simulation, a global convection appears after radial segregation pattern is formed, and this convection induces axially segregated pattern. PACS number(s): 45.70.-n, 45.70.Mg Granular materials exhibit some complex phenomena. One example is size segregation which occurs by shaking or stirring them3–10. Mixtures of granular materials which are partially-filled in horizontally rotating drum also segregate by size. Recent experiments of such rotating drum have shown two types of segregation patterns. One of them is radial segregation where large materials accumulate near the walls of drum and small materials ∗E-mail: [email protected]