Modelling the Flow Rate Dip for a Silo with Two Openings

In recent experiments it was shown that a planar silo with two discharge orifices which were separated by a distance, L, displayed counter-intuitive flow rate phenomenon. In contrast to previous studies, the flow rate did not monotonically decrease as the separation between orifices increased. Instead, a rapid decrease in flow rate was observed as the two orifices were separated until, at a critical orifice separation, a minimum flow rate was reached. Upon further separating the two orifices the flow rate steadily increased to the infinite separation limit of two openings. In this work we numerically investigate this so-called ‘flow-rate dip’ phenomenon. The kinematic and the \(\mu (I)\) models are used to examine the two opening silo, with the kinematic model failing to capture any flow rate dynamics and the \(\mu (I)\) model capturing the dynamics if appropriately large (yet still physically reasonable) friction parameters are used.