Negative drag force on beating flagellar-shaped bodies in active fluids

Abstract

We experimentally investigate the drag force exerted by a suspension of light-induced active particles (APs) on a translating and beating idealized flagellum-shaped object realized through negative phototactic interactions with the APs. We observe both positive and negative drag forces, depending on the beating frequency and translational velocity, driven by the dynamic redistribution of APs in response to the object's motion. These findings are supported by numerical simulations and an analytical model, extendable to a range of slender geometries. Our results illustrate the complex interplay between geometric body changes and the density distribution in active baths, which may also be relevant for microrobotic applications.

to appear in PRL

References in corpus (27)

• Active Particles in Complex and Crowded Environments
• Fluid dynamics and noise in bacterial cell-cell and cell-surface scattering
• A bacterial ratchet motor
• Microswimmers in Patterned Environments
• Sedimentation of active colloidal suspensions
• Active Brownian Motion Tunable by Light
• Phototaxis of synthetic microswimmers in optical landscapes
• Dynamics of Self-Propelled Particles Under Strong Confinement
• Active particles with soft and curved walls: Equation of state, ratchets, and instabilities
• Fluctuations and Rheology in Active Bacterial Suspensions
• Swim pressure on walls with curves and corners
• Loopy Lévy flights enhance tracer diffusion in active suspensions
• Dynamics and density distribution of strongly confined noninteracting nonaligning self-propelled particles in a nonconvex boundary
• Tuning the motility and directionality of self-propelled colloids
• The Anomalous Transport of Tracers in Active Baths
• Active Brownian particles near straight or curved walls: Pressure and boundary layers
• Collective forces in scalar active matter
• Minimum Dissipation Theorem for Microswimmers
• Effective interactions between inclusions in an active bath
• On the Einstein relation between mobility and diffusion coefficient in an active bath
• Thermodynamics of active matter: Tracking dissipation across scales
• Transient coarsening and the motility of optically heated Janus colloids in a binary liquid mixture
• Vorticity Determines the Force on Bodies Immersed in Active Fluids
• Effective dynamics and fluctuations of a trapped probe moving in a fluid of active hard discs
• Motility-induced clustering of active particles under soft confinement
• Active particles confined in deformable droplets
• Gauging nanoswimmer dynamics via the motion of large bodies