There has been sufficient research on the factors that affect the mass discharge rate (MDR) of particles in silos, but the relevant physical mechanism has always been lacking. In current works, a mathematical model is established between macroscopic MDR and microscopic wall friction by changing the side wall materials of the eccentric silo. Thus achieving control over a range of up to 40% variation in mass discharge rate. Furthermore, the velocity of particles is measured using the optical flow method, then the structure of free-fall arch and the velocity of particles on the arch are obtained. It is revealed that the variation of MDR is caused by the change in geometric structure of free-fall arch. Surprisingly, the velocity of particles on the arch is the same at different heights under different MDR. The reason is that under high frictional coefficient, the gravitational potential energy of particles is more dissipated in the rotational motion caused by resistance. This work explains for the first time the regulation mechanism of the frictional coefficient on MDR, and provides a data reference for improving the theoretical model of MDR.

Frictional coefficient; Mass discharge rate; Free-fall arch; Eccentric silos