López-Rodríguez Diego, Gella Diego, To Kiwing, Maza Diego, Garcimartín Angel, Zuriguel Iker
Departamento de Física, Facultad de Ciencias, Universidad de Navarra, E-31080 Pamplona, Spain.
Institute of Physics, Academia Sinica, Taipei 115, Taiwan.
Phys Rev E. 2019 Mar;99(3-1):032901. doi: 10.1103/PhysRevE.99.032901.
We present experimental results of the effect of the hopper angle on the clogging of grains discharged from a two-dimensional silo under gravity action. We observe that the probability of clogging can be reduced by three orders of magnitude by increasing the hopper angle. In addition, we find that for very large hopper angles, the avalanche size (〈s〉) grows with the outlet size (D) stepwise, in contrast to the case of a flat-bottom silo for which 〈s〉 grows smoothly with D. This surprising effect is originated from the static equilibrium requirement imposed by the hopper geometry to the arch that arrests the flow. The hopper angle sets the bounds of the possible angles of the vectors connecting consecutive beads in the arch. As a consequence, only a small and specific portion of the arches that jam a flat-bottom silo can survive in hoppers.
我们展示了料斗角度对二维筒仓在重力作用下排出谷物堵塞情况影响的实验结果。我们观察到，通过增加料斗角度，堵塞概率可降低三个数量级。此外，我们发现，对于非常大的料斗角度，雪崩规模（〈s〉）随出口尺寸（D）逐步增大，这与平底筒仓中〈s〉随D平滑增大的情况形成对比。这种惊人的效果源于料斗几何形状对阻止流动的拱施加的静态平衡要求。料斗角度设定了连接拱中连续珠子的向量可能角度的界限。因此，只有一小部分堵塞平底筒仓的拱能在料斗中留存。
