LMP Seminar: Lorentz reciprocal theorem in chiral active fluids with odd viscosity

LMP Seminar

  • Datum: 28.02.2024
  • Uhrzeit: 14:00 - 15:30
  • Vortragende(r): Dr. Yuto Hosaka
  • Dept. of Living Matter Physics, MPI for Dynamics and Self-Organization
  • Ort: Max-Planck-Institut für Dynamik und Selbstorganisation (MPIDS)
  • Raum: Riemannraum 1.40 & ZOOM Meeting ID: 997 1155 2453 Passcode: 771001
  • Gastgeber: MPIDS / LMP
  • Kontakt: golestanian-office@ds.mpg.de
Chiral active fluids with broken time-reversal and parity symmetries are prevalent at various scales in nonequilibrium systems, ranging from electron fluids to biological and geophysical flows. In such fluids, a peculiar transport coefficient called odd viscosity arises. This viscosity, which does not contribute to the fluid energy dissipation, leads to novel dynamics, such as nonreciprocal (transverse) transports, free-surface dynamics, or chiral edge currents characterized by topological protection, akin to quantum Hall systems. The lack of time-reversal symmetry leads to an asymmetric response and, thus, to an asymmetric mobility tensor. This suggests that the Lorentz reciprocal theorem, a powerful and versatile principle in low-Reynolds-number fluid dynamics, is violated in chiral active fluids.

In this talk, I will present my recent work on the generalization of the Lorentz reciprocal theorem in chiral active fluids with odd viscosity [1]. First, we show the derivation of the theorem in the presence of odd viscosity by choosing an auxiliary problem with the opposite sign of the viscosity. Then, as an application of the extended theorem in active matter systems, we use it to determine the swimming velocity of two categories of microswimmers in a Stokes fluid with odd viscosity. We show that a surface-driven microswimmer, which we call a “twister”, can exhibit vertical dynamics induced by nonreciprocal responses due to the odd viscosity. Our theoretical results will facilitate the solution of a number of swimming and flow problems in fluids with odd viscosity and should be applicable to various chiral active systems.

[1] Y. Hosaka, R. Golestanian, and A. Vilfan, Phys. Rev. Lett. 131, 178303 (2023)
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