Granular materials can behave like solids and fluids exhibiting complex mechanical behavirors. We conduct studies on the granular materials in the physical perspective to discover the physical mechanisms of the mechanical behaviors of granular materials. Thus, we can deepen our understandings on the mysterious materials. 

(1) Kinematic and energy characteristic of a granular flow

We develop a plate shear model to study the kinematic and energy characteristics of granular flows. The inertial number is used to distinguish different flow regimes. Linear/angular velocity profiles, force chains and other qualities are compared for different regions. 

(2) Structural signature for the solid-fluid transition

We summarize the popular structural analysis tools and classified them into different strategies. We adopt the radial tessellation to analyze the topological states and find that the fivefold symmetry is a critical structural signature. The region holding high fivefold symmetry is linked with the shear bands. Based on our understanding of mesoscopic structures, we define a structure unit to explain the transition between solid-like and fluid-like behaviors.

Summary of structural analysis tools

                             A structural granular assembly unit.