Granular flow fluctuations in a conical hopper

In this article, we present simulations of 3D hopper flows through conical hoppers, with a focus on time fluctuations of flow-related quantities (velocity, coordination number and solid fraction). Dedicated post-processing techniques are used to obtain local and yet statistically meaningful measurements of these quantities. Simulations show that the fluctuations that were already observed in 2D hopper flows are still present in 3D. A parametric study also demonstrates that the frequency of the fluctuations is strongly related to the stiffness parameter of the contact law used in the simulations