Transport and dispersion of active particles in periodic porous media

Abstract

The transport of self-propelled particles such as bacteria and phoretic swimmers through crowded heterogeneous environments is relevant to many natural and engineering processes, from biofilm formation and contamination processes to transport in soils and biomedical devices. While there has been experimental progress, a theoretical understanding of mean transport properties in these systems has been lacking. In this work, we apply generalized Taylor dispersion theory to analyze the long-time statistics of an active self-propelled Brownian particle transported under an applied flow through the interstices of a periodic lattice that serves as an idealization of a porous medium. Our theoretical model, which we validate against Brownian dynamics simulations, is applied to unravel the roles of motility, fluid flow, and lattice geometry on asymptotic mean velocity and dispersivity. In weak flows, transport is dominated by active dispersion, which results from self-propulsion in the presence of noise and is hindered by the obstacles that act as entropic barriers. In strong flows, shear-induced Taylor dispersion becomes the dominant mechanism for spreading, with pillars now acting as regions of shear production that enhance dispersion. The interplay of these two effects leads to complex and unexpected trends, such as a non-monotonic dependence of axial dispersivity on flow strength and a reduction in dispersion due to swimming activity in strong flows. Brownian dynamics are used to cast light on the pre-asymptotic regime, where tailed distributions are observed in agreement with recent experiments on motile micro-organisms. Our results also highlight the subtle effects of pillar shape, which can be used to control the magnitude of dispersion and to drive a net particle migration in quiescent systems.

arXiv comment21 pages, 12 figures

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Cited by in corpus (26)

• A Geometric Criterion for the Optimal Spreading of Active Polymers in Porous Media
• Chirality-induced bacterial rheotaxis in bulk shear flows
• Swimming in Complex Fluids
• Controlling effective dispersion within a channel with flow and active walls
• Active Brownian and inertial particles in disordered environments: short-time expansion of the mean-square displacement
• Effective diffusivity of microswimmers in a crowded environment
• Crowding-Enhanced Diffusion: An Exact Theory for Highly Entangled Self-Propelled Stiff Filaments
• Transient dispersion process of active particles
• Geometric effects induce anomalous size-dependent active transport in structured environments
• Dispersion of motile bacteria in a porous medium
• Capillary action in scalar active matter
• Directional Locking Effects for Active Matter Particles Coupled to a Periodic Substrate
• Active Matter Commensuration and Frustration Effects on Periodic Substrates
• The Influence of Motility on Bacterial Accumulation in a Microporous Channel
• Deflection of phototactic microswimmers through obstacle arrays
• Active Matter Invasion
• Clogging, Dynamics and Reentrant Fluid for Active Matter on Periodic Substrates
• Pushing run-and-tumble particles through a rugged channel
• Future Directions for Active Matter on Ordered Substrates
• Rotational Taylor dispersion in linear flows
• Activity-induced asymmetric dispersion in confined channels with constriction
• Macrotransport of active particles in periodic channels and fields: rectification and dispersion
• Transport of a passive scalar in wide channels with surface topography
• Geometric frustration and pairing order transition in confined bacterial vortices
• Is Chaotic Advection Inherent to Heterogeneous Darcy Flow?
• Self-organised structures in mixed active-passive suspensions due to hydrodynamic interactions