Nature of collective motion in dilute suspensions of self-propelled particles
Nature of collective motion in dilute suspensions of self-propelled particles
- Event time: 1:00pm
- Event date: 12th October 2015
- Speaker: Professor Alexander Morozov (School of Physics & Astronomy, University of Edinburgh)
- Location: Room 2511, James Clerk Maxwell Building (JCMB) James Clerk Maxwell Building Peter Guthrie Tait Road Edinburgh EH9 3FD GB
Event details
Recent years have witnessed a significant interest in physical, biological and engineering aspects of self-propelled particles, such as bacteria or synthetic microswimmers. The main distinction of this 'active matter' from its passive counterpart is the ability to extract energy from the environment (consume food) and convert it into directed motion.
One of the most striking consequences of this distinction is the transition to collective motion in self-propelled particles suspended in a fluid observed in recent experiments: at low densities particles move around in an uncorrelated fashion, while at higher densities they organise into jets and vortices comprising many individual swimmers. Presently, very little is understood about the origin of this transition.
In this talk I will propose a possible mechanism responsible for the transition to collective motion in model swimmers. First I will present a numerical method based on a Lattice-Boltzmann algorithm to simulate hydrodynamic interactions between a large number of model swimmers (order 10^5), represented by extended force dipoles.
Using this method we simulate the transition to large-scale structures, and use a simple hydrodynamic theory to characterise them. I will discuss the nature of the coherent state, velocity fluctuations and turbulent-like spectra observed in this state and present results on the influence of coherent motion on the enhanced diffusion of tracer particles suspended in a solution of microswimmers.
About Condensed Matter lunchtime seminars
This is a weekly series of informal talks given primarily by members of the institute of condensed matter and complex systems, but is also open to members of other groups and external visitors. The aim of the series is to promote discussion and learning of various topics at a level suitable to the broad background of the group. Everyone is welcome to attend..