Berlin 2012 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 2: Statistical Physics (General)

DY 2.3: Talk

Monday, March 26, 2012, 10:15–10:30, MA 004

Explosive condensation in a mass transport model — •Bartlomiej Waclaw and Martin Evans — School of Physics, University of Edinburgh

Recent studies in non-equilibrium statistical physics show that diverse phenomena such as jamming in traffic flow, wealth condensation in macroeconomies or hub formation in complex networks can be understood by the condensation transition, in which a finite fraction of the system mass becomes localized in space. A classical model of condensation is the Zero-Range Process (ZRP) in which particles hop between sites of a 1d lattice with the rate which decreases with the number of particles at the departure site. This causes the condensate to evolve more slowly, the more particles it has. Therefore, the condensate remains static once it has formed, melting and reforming very rarely. In his talk we demonstrate a completely different mechanism of condensation, motivated by processes such as gravitational clustering or formation of droplets in clouds, where aggregation of particles speeds up in time as a result of increasing exchange rate of particles between growing clusters. In our model, particles hop between lattice sites with the rate u(m,n) which increases with the numbers m,n of particles at interacting sites. We show that condensation occurs in this model through a contrasting dynamical mechanism to that previously considered --- the formation of the condensate happens on a very fast time scale and we term it explosive.