Velocity scaling of granular flow in silos under different discharge modes

Accurately measuring the velocity field of granular flow in silos and elucidating the distribution law under different discharge modes are essential for understanding the mechanisms of granular rheology and optimizing discharge system design. This work investigates the flow characteristics of black electroplated glass beads in a two-dimensional silo under free-fall discharge and conveyor-belt discharge. The particle tracking velocimetry (PTV) method is employed to measure the velocity field, and the distribution characteristics under the two modes are systematically compared and analyzed. The results show that although there are significant differences in the numerical values of granular velocity, the normalized velocity profiles remain highly consistent. On this basis, a quantitative relationship between the velocity profiles under the two discharge modes is established through the kinematic model. This reveals that the differences in velocity profiles caused by the discharge modes essentially correspond to magnitude scaling, while the overall flow characteristics remain invariant. This finding not only provides a predictive model for the velocity field under conveyor-belt discharge in silos but also contributes empirical data to advance the rheological theory of granular flow.