We present an experimental study of the discharge of a monolayer of a ferromagnetic granular medium in a quasi-2D silo surrounded by vertical uniform magnetic field. We observe that the cohesion induced by the vertical magnetic field tends to canalize the flow above the outlet, modifying its morphology with little incidence on the mass flow rate. Using a direct measurement method of velocities based on particle tracking, we are able to extract an altitude-dependent diffusion length of the granular medium, previously introduced in the kinetic model, and propose a qualitative interpretation of its decay with cohesion.
Luce et al. (2025) studied this question.