School Seminars and Colloquia

Colloquium: Aggregation-pattern in non-local equations with locally-repulsive interaction potentials


by Dr Klemens Fellner

Institution: University of Cambridge and University of Vienna
Date: Tue 20th April 2010
Time: 12:00 PM
Location: Russell Love Theatre, Richard Berry Bldg, The Uni of Melb

Abstract: We study non-local evolution equations for a density of individuals, which interact through a given symmetric potential. Such models appear in many applications such as swarming and flocking, opinion formation, inelastic materials, .... In particular, we are interested in interaction potentials, which behave locally repulsive, but aggregating over large scales. A particular example for such potentials was recently given in models of the alignment of the directions of filaments in the cytoskeleton.

We present results on the structure and stability of steady states. We shall show that stable stationary states of regular interaction potentials generically consist of sums of Dirac masses. However the amount of Diracs depends on the interplay between local repulsion and aggregation. In particular we shall see that singular repulsive interaction potentials introduce diffusive effects in the sense that stationary state are no longer sums of Diracs but continuous densities.

For More Information: Contact Paul Pearce ( or Paul Norbury (

Colloquium Website