Diffusion Under Confinement: A journey Through Counterintuition
Leonardo Dagdug (UAM, Mexico)
Diffusion is one of the most fundamental transport processes in nature, yet its behavior under geometric confinement often defies intuition. In this seminar, I will discuss how boundaries, channel geometry, and spatial restrictions profoundly alter transport properties, giving rise to unexpected phenomena that are absent in unbounded media. Particular attention will be devoted to the Fick-Jacobs equation, an effective description that reduces transport in complex confined geometries to a one-dimensional problem while incorporating entropic effects. Through several illustrative examples, I will show how confinement can generate nontrivial diffusion dynamics throughout effective diffusivity. I will conclude by touching upon recent developments in diffusion with stochastic resetting, where the interplay between randomness, confinement, and resetting gives rise to novel nonequilibrium phenomena, unusual first-passage properties, and unexpected transport behavior.