Activity-induced isotropic-polar transition in active liquid crystals

¹ Dipartimento di Fisica, Università degli Studi di Bari and INFN, Sezione di Bari via Amendola 173, Bari, I-70126, Italy
² Dipartimento di Meccanica, Matematica e Management, DMMM, Politecnico di Bari - 70125, Bari, Italy
³ Instituut- Lorentz, Universiteit Leiden - P.O. Box 9506, 2300 RA Leiden, The Netherlands

Received: 16 October 2020
Accepted: 17 February 2021

Abstract

Active fluids are intrinsically out-of-equilibrium systems due to the internal energy injection of the active constituents. We show here that a transition from a motion-less isotropic state towards a flowing polar one can be possibly driven by the sole active injection through the action of polar-hydrodynamic interactions in absence of an ad hoc free energy which favors the development of an ordered phase. In particular, we propose an analytical argument and we perform lattice Boltzmann simulations where the appearance of large temporal fluctuations in the polar fraction of the system is observed at the transition point. We show that elastic absorption plays a relevant role in energy transfer dynamics, contrary to the case of the usual active gel theory where this term can be factually neglected.