## Aggregation and fragmentation kinetics. Application to Planetary Rings.

**Note:**Pizza served at 11:45 AM; Note Special Location

**Speaker:**Nikolay Brilliantov, University of Leicester, Leicester, UK

**When:**May 15, 2015 (Fri), 12:00PM to 01:00PM (add to my calendar)

**Location:**SCI 328

**Hosted by:**Paul Krapivsky

*This event is part of the Biophysics/Condensed Matter Seminar Series. *

Abstract: Kinetics of ballistic aggregation and fragmentation is studied for a set of microscopic aggregation and fragmentation models. We describe evolution of a system of interacting particles using the Enskog-Boltzmann equation for the mass-velocity distribution function. We derive Smoluchowski-like equations for concentrations of particles of different mass and for their mean kinetic energy. We analyze these equations analytically and numerically. For the case of lacking fragmentation we observe several evolution regimes, if however, fragmentation is present, the system evolves to a steady state. We reveal universality of the particle size distribution for the steady state. Namely, we show that if fragmentation occurs with a strong dominance of small pieces, the resulting steady-state distribution does not depend on a microscopic fragmentation mechanism. Application to the Saturn Rings demonstrates a good agreement between the observation data and the theory.