Bauyrzhan Primkulov, Massachusetts Institute of Technology

Avalanches in Strong Imbibition

Earthquakes, landslides, avalanches, solar flares, and financial markets are examples of self-organized criticality (SOC), a near-equilibrium process where small perturbations lead to scale-free (and thereby essentially unpredictable) consequences. A classic example of SOC is the drainage of a wetting fluid from a porous medium (Furuberg et al., PRL 1988). In drainage, the wetting fluid retreats preferentially from pore bodies as the non-wetting fluid invades. Reversing the flow direction leads instead to imbibition, where the wetting fluid invades by preferentially coating the solid surfaces. Here, we show with experiments and simulations that strong imbibition shares all of the scale-free features of drainage—avalanches, intermittency, and spatiotemporal correlation scaling—a striking finding, given that these two processes occur through radically different displacement mechanisms at the pore scale.