Force-induced dispersion in heterogeneous media

Thomas Guérin (1) , David S. Dean (1)

1 LOMA - Laboratoire Ondes et Matière d'Aquitaine

The effect of a constant applied external force, induced for instance by an electric or gravitational field, on the dispersion of Brownian particles in periodic media with spatially varying diffusivity, and thus mobility, is studied. We show that external forces can greatly enhance dispersion in the direction of the applied force and also modify, to a lesser extent and in some cases non-monotonically, dispersion perpendicular to the applied force. Our results thus open up the intriguing possibility of modulating the dispersive properties of heterogeneous media by using externally applied force fields. These results are obtained via a Kubo formula which can be applied to any periodic advection diffusion system in any spatial dimension.

Mots clés: Brownian motion; Classical transport; Stochastic processes; Stochastic analysis methods; Fluctuation phenomena; random processes; noise

Domaines: Mécanique statistique [cond-mat.stat-mech]

Thomas Guérin, David S. Dean. Force-induced dispersion in heterogeneous media. Physical Review Letters, 2015, 115 (2), pp.020601 (1-5). ⟨10.1103/PhysRevLett.115.020601⟩. ⟨hal-01182313⟩