GAFD Seminar: Hollis Williams

Intermittent, threshold-driven behaviour is a recurring feature of magnetised geophysical and astrophysical systems, where magnetic stresses accumulate slowly and are released through discrete events. In this talk I will discuss a complementary perspective based on magnetic granular media: assemblies of interacting magnetic particles which evolve through sequences of stable configurations followed by sudden rearrangements. I will review experimental and numerical results for these systems, highlighting how magnetic interactions lead to collective reorganisation, intermittency, and avalanche-like behaviour under slow driving. These systems provide a reduced setting in which magnetic stress, connectivity, and structural anisotropy can be studied without the full complexity of conducting fluid flows.