Granular Flow in 3D Silo with Rotating Exit Kiwing To ^{1*}^{1}Institute of Physics, Academia Sinica, Taipei, Taiwan* Presenter:Kiwing To, email:ericto@gate.sinica.edu.tw We conducted granular flow experiments of mono-disperse plastic beads falling out of a three-dimensional cylindrical silo through a circular exit at the bottom. When the diameter of the exit is about 5 times that of the beads, no finite flow rate can be sustained indefinitely because of clogging occurring at the exit. We constructed a silo with a bottom that can rotate with respect to the wall of the silo. One can drive the bottom of the silo so that the exit rotates or moves in a circle if the exit is off centered. In such a silo with rotating bottom, finite flow rate can be sustained indefinitely. It is found that the effect of rotation is negligible when the exit diameter is large as compared to the grain size. On the other hand, when the exit diameter is small, flow rate Q increases with the angular frequency ω of the rotating bottom as well as the distance R of the exit from the axis of the silo. Interestingly, Q at different ω and R collapse to a single curve when plotted against the product of ω and R. A simple theory is proposed to explain the observed dependence of Q on R and ω.
Keywords: granular flow , clogging, silo |