Granular flow dynamics in a vibrating system from multiple points of view: Laboratory experiments, continuum modeling, and numerical simulations

This study investigates granular flow dynamics in a vibrating system from multiple directions: laboratory experiments, continuum modeling, and numerical simulations. In the experiment, a conical granular pile is subjected to vertical vibration. Depending on its strength, granular particles are fluidized, and the shape of the pile is gradually relaxed. During the vibration, the relaxing pile is observed by a high-speed laser profiler. Based on those data, we have proposed a continuum model, which can predict how the flux of granular particles is determined. This model has only one fitting parameter that indicates the conversion efficiency from inputted vibration energy into granular transport energy. By comparing the experimental data obtained under various conditions, this parameter turned out to be a universal constant. In order to consolidate this universality and explore the flow property inside the pile, a series of particle-scale numerical simulations have also been conducted. As a result, we have confirmed that the continuum model is satisfied and the conversion efficiency does not change in numerical simulations. We have also found that the velocity decreases exponentially from the surface of a pile, which suggests the presence of shear-band structure.