SKM 2023 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 38: Microswimmers and Fluid Physics of Life (joint session DY/CPP)

CPP 38.4: Talk

Wednesday, March 29, 2023, 15:45–16:00, MOL 213

Minimum Entropy Production by Microswimmers with Internal Dissipation — •Andrej Vilfan, Abdallah Daddi-Moussa-Ider, Babak Nasouri, and Ramin Golestanian — Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany

Microswimmers are natural or artificial self-propelled microscale objects moving through a fluid at low Reynolds numbers. The entropy production of microswimmers, related to their dissipated power, consists of two contributions. The external dissipation takes place in the viscous fluid surrounding the microswimmer. Internal dissipation takes place in the propulsive layer on the swimmer's surface. We have previously shown that a lower bound on the external dissipation can be derived with the knowledge of drag coefficients of two bodies of the same shape, one with a no-slip and one with a perfect slip boundary condition [1]. Here, we show that our approach can be generalized to take into account the internal dissipation, which is often the dominant contribution. By combining the Helmholtz minimum dissipation theorem and the principle of linear superposition, we solve the combined minimum dissipation problem for different classes of swimmers including surface-driven viscous droplets, swimmers driven by tangential forces and swimmers driven by normal forces. We show that the minimum entropy production in suspensions of active microswimmers differs fundamentally from particles driven by external forces.

[1] B. Nasouri, A. Vilfan and R. Golestanian, Phys. Rev. Lett., 126, 034503 (2021).