Lattice-Boltzmann Simulations of Microswimmer-Tracer Interactions

Abstract

Hydrodynamic interactions in systems comprised of self-propelled particles, such as swimming microorganisms, and passive tracers have a significant impact on the tracer dynamics compared to the equivalent "dry" sample. However, such interactions are often difficult to take into account in simulations due to their computational cost. Here, we perform a systematic investigation of swimmer-tracer interaction using an efficient force/counter-force based lattice-Boltzmann (LB) algorithm [J. de Graaf~\textit{et al.}, J. Chem. Phys.~\textbf{144}, 134106 (2016)] in order to validate its ability to capture the relevant low-Reynolds-number physics. We show that the LB algorithm reproduces far-field theoretical results well, both in a system with periodic boundary conditions and in a spherical cavity with no-slip walls, for which we derive expressions here. The force-lattice coupling of the LB algorithm leads to a "smearing out" of the flow field, which strongly perturbs the tracer trajectories at close swimmer-tracer separations, and we analyze how this effect can be accurately captured using a simple renormalized hydrodynamic theory. Finally, we show that care must be taken when using LB algorithms to simulate systems of self-propelled particles, since its finite momentum transport time can lead to significant deviations from theoretical predictions based on Stokes flow. These insights should prove relevant to the future study of large-scale microswimmer suspensions using these methods.

References in corpus (18)

• Active Particles in Complex and Crowded Environments
• The hydrodynamics of swimming microorganisms
• Physics of Microswimmers - Single Particle Motion and Collective Behavior
• Fluid dynamics and noise in bacterial cell-cell and cell-surface scattering
• Hydrodynamics of self-propulsion near a boundary: predictions and accuracy of far-field approximations
• Direct measurement of the flow field around swimming microorganisms
• Fluid Flows Created by Swimming Bacteria Drive Self-Organization in Confined Suspensions
• Diffusion and spatial correlations in suspensions of swimming particles
• Run-and-tumble particles with hydrodynamics: sedimentation, trapping and upstream swimming
• Orientational order in concentrated suspensions of spherical microswimmers
• Entrainment dominates the interaction of microalgae with micron-sized objects
• Singular forces and point-like colloids in lattice Boltzmann hydrodynamics
• Lattice-Boltzmann Hydrodynamics of Anisotropic Active Matter
• Swimmer-tracer scattering at low Reynolds number
• Many-body microhydrodynamics of colloidal particles with active boundary layers
• Understanding the Onset of Oscillatory Swimming in Microchannels
• Fluid transport and mixing by an unsteady microswimmer
• Stirring by Periodic Arrays of Microswimmers

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• Particle-resolved lattice Boltzmann simulations of 3-dimensional active turbulence
• A Lattice Boltzmann Model for Squirmers
• Influence of thermal fluctuations on active diffusion at large Péclet numbers
• Interplay between Brownian and hydrodynamic tracer diffusion in suspensions of swimming microorganisms
• Pseudo-giant number fluctuations and nematic order in microswimmer suspensions