Minimum Entropy Production by Microswimmers with Internal Dissipation

TL;DR

This paper derives a fundamental lower bound on the total energy dissipation of microswimmers, revealing how their shape and propulsion mechanisms influence entropy production differently from passive particles.

Contribution

It introduces a general theorem that precisely bounds the internal and external dissipation of microswimmers, applicable to various propulsion models and shapes.

Findings

Derived an exact lower bound on microswimmer dissipation.

Identified optimal shapes minimizing total dissipation.

Showed fundamental differences in entropy limits compared to passive particles.

Abstract

The energy dissipation and entropy production by self-propelled microswimmers differ profoundly from passive particles pulled by external forces. The difference extends both to the shape of the flow around the swimmer, as well as to the internal dissipation of the propulsion mechanism. Here we derive a general theorem that provides an exact lower bound on the total, external and internal, dissipation by a microswimmer. The problems that can be solved include an active surface-propelled droplet, swimmers with an extended propulsive layer and swimmers with an effective internal dissipation. We apply the theorem to determine the swimmer shapes that minimize the total dissipation while keeping the volume constant. Our results show that the entropy production by active microswimmers is subject to different fundamental limits than the entropy production by externally driven particles.