  We used the discrete element method (DEM) to study the flow dynamics of a
mixture of dumbbells and discs for two silo cases: 1. orifice situated on the
lateral wall and 2. multiple orifices placed on the base of a two-dimensional
silo. The time-averaged flow fields of various parameters like velocity, area
fraction, pressure, shear stress etc, obtained from coarse-graining technique
are presented for both the above-mentioned cases. A modified Beverloo scaling
is reported for the flow discharging through the lateral orifice. The dynamic
friction is found to increase with an increase in the addition of dumbbells.
This resulted in a decrease in the flow rate through a lateral orifice with the
addition of dumbbells. Self-similar velocity profiles are observed for mixtures
for the whole range of lateral orifice widths studied. The flow rate decreases
with an increase in the inter-orifice distance L/d for the multiple orifice
case. The velocity profile and flow fields revealed an interaction zone between
the two orifices at small L/d which is almost absent when the orifices are wide
apart. This interaction zone or flow through an orifice influenced by the
presence of an adjacent orifice is the reason for a higher velocity above each
of the orifices thus resulting in a higher flow rate at small L/d. The stagnant
zone between the orifices is found to expand with an increase in the
inter-orifice distance which yields in an increase in the shear stress between
each of the orifices and the stagnant zone.
