Active carpets drive non-equilibrium diffusion and enhanced molecular fluxes.

ABSTRACT: Biological activity is often highly concentrated on surfaces, across the scales from molecular motors and ciliary arrays to sessile and motile organisms. These 'active carpets' locally inject energy into their surrounding fluid. Whereas Fick's laws of diffusion are established near equilibrium, it is unclear how to solve non-equilibrium transport driven by such boundary-actuated fluctuations. Here, we derive the enhanced diffusivity of molecules or passive particles as a function of distance from an active carpet. Following Schnitzer's telegraph model, we then cast these results into generalised Fick's laws. Two archetypal problems are solved using these laws: First, considering sedimentation towards an active carpet, we find a self-cleaning effect where surface-driven fluctuations can rep

SUBMITTER: Guzman-Lastra F 

PROVIDER: S-EPMC7997990 | biostudies-literature | 2021 Mar

REPOSITORIES: biostudies-literature