Eur. Phys. J. E (2016) 39: 1
https://doi.org/10.1140/epje/i2016-16001-2

Regular Article

Spontaneous flow in polar active fluids: the effect of a phenomenological self propulsion-like term

¹ Dipartimento di Fisica, Università di Bari, and INFN, Sezione di Bari, Via Amendola 173, 70126, Bari, Italy
² Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, I-35131, Padova, Italy
³ School of Physics and Astronomy, University of Edinburgh, JCMB Kings Buildings, Peter Guthrie Tait Road, EH9 3FD, Edinburgh, United Kingdom

^* e-mail: bonellifra@alice.it
^** e-mail: tiribocchi@pd.infn.it

Received: 4 September 2015
Accepted: 2 December 2015
Published online: 14 January 2016

Abstract

We present hybrid lattice Boltzmann simulations of extensile and contractile active fluids where we incorporate phenomenologically the tendency of active particles such as cell and bacteria, to move, or swim, along the local orientation. Quite surprisingly, we show that the interplay between alignment and activity can lead to completely different results, according to geometry (periodic boundary conditions or confinement between flat walls) and nature of the activity (extensile or contractile). An interesting generic outcome is that the alignment interaction can transform stationary active patterns into continuously moving ones: the dynamics of these evolving patterns can be oscillatory or chaotic according to the strength of the alignment term. Our results suggest that flow-polarisation alignment can have important consequences on the collective dynamics of active fluids and active gel.