Generalized Archimedes' principle in active fluids

Abstract

We show how a gradient in the motility properties of non-interacting point-like active particles can cause a pressure gradient that pushes a large inert object. We calculate the force on an object inside a system of active particles with position dependent motion parameters, in one and two dimensions, and show that a modified Archimedes' principle is satisfied. We characterize the system, both in terms of the model parameters and in terms of experimentally measurable quantities: the spatial profiles of the density, velocity and pressure. This theoretical analysis is motivated by recent experiments, which showed that the nucleus of a mouse oocyte (immature egg cell) moves from the cortex to the center due to a gradient of activity of vesicles propelled by molecular motors; it more generally applies to artificial systems of controlled localized activity.

arXiv comment16 pages, 9 figures

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Cited by in corpus (12)

• Broken detailed balance and non-equilibrium dynamics in living systems
• Stationary superstatistics distributions of trapped run-and-tumble particles
• Sedimentation of self-propelled Janus colloids: polarization and pressure
• Chemotaxis of cargo-carrying self-propelled particles
• The entropy production of an active particle in a box
• Run-and-Tumble particle in inhomogeneous media in one dimension
• Confinement-induced accumulation and spontaneous de-mixing of microscopic active-passive mixtures
• Shape matters: A Brownian microswimmer in a channel
• Force generation in confined active fluids: The role of microstructure
• Forces in inhomogeneous open active-particle systems
• Active noise-driven particles under space-dependent friction in one dimension
• Colloidal Brazil nut effect in microswimmer mixtures induced by motility contrast