Flow rate characterization for liquid-immersed granular medium discharging through a hopper

The granular sample immersed in a viscous fluid discharge through an orifice connecting a pipe or no pipe has been numerically investigated. A two-dimensional fluid-particle model is adapted, which combines the discrete element method with the lattice Boltzmann method using the partial saturation boundary technique. The discharge rate of liquid-immersed granular media flowing from a hopper is parametrically analyzed by adding a pipe at the outlet, varying fluid properties and orifice sizes. The results show that the existence of the pipe significantly slows down the discharge rate compared with the no-pipe case. A revisited law based on the experimental investigations is proposed by incorporating particle maximum velocity, enabling the prediction of the discharge rate properly. To account for the fluid-particle interaction, the velocity distribution of the particle and its surrounding fluid is analyzed at the local scale. Then, an extension of the kinematic model linking the particle flow rate and velocity distribution is proposed, which allows the prediction of granular discharge from a hopper by considering the influence of the interstitial fluid.