Mesoscopic evolution and kinetic properties of dense granular flow crystallization under continuous shear induction

Abstract

The influence of spatial structure on the kinetic response of discrete soft matter is critical. The exploration is not limited to structural evolution, jamming point, phase transition, etc. However, the mesoscopic response under continuous loading has always been difficult to make progress in experiments. In this study, we explored the mesoscopic evolution and properties of the ordered structure in dense granular flow under continuous shear by experiments and simulations. It shows that the crystal structure of the particles develops simultaneously inward from the boundary of the shearing cell. Two morphological clusters formed one after another within a 2D cylindrical layer parallel to the boundary. At the single-particle level, continuous strain is found to make the crystallization process within the cylindrical layers an evolution of chain-like polycrystalline to monocrystal structures. Compared to oscillatory shear, splicing or fusion is the way to reach the final state from the transition state under continuous shear rather than epitaxial growth. Due to continuous shear, the symmetry of the crystal switches between hexagonal close-packed (HCP) and face-centered cubic (FCC) and is dynamically balanced in the flow. We also describe the switching path. The results show that HCP in flow is more favored by the environment than FCC.