Movement mechanisms of solid-like and liquid-like motion states in a vibrating granular bed

In this study we analyze the granular motion and the variation in energy on the surface of a vibrating bed as well as the flow regime inside the bed. The variation in the granular kinetic energy at the free surface of the bed under different vibration conditions produces the following motion states: solid-like state, transition region and liquid-like state. The granular kinetic energy is measured and found to increase slowly until the vibration acceleration reaches the first specific dimensionless vibration acceleration ΓI. The granular kinetic energy increases sharply as the vibration acceleration continues to increase after exceeding ΓI until reaching the second specific dimensionless vibration acceleration ΓII. The granular kinetic energy increases with the vibration acceleration afterwards. The movement mechanism inside the granular bed is transformed from particle reorganization to surface convection as the bed state transfers from a solid-like state to a liquid-like state.