Asymptotics of blowup solutions for the aggregation equation

We consider the asymptotic behavior of radially symmetric solutions of the aggregation equation ut = ∇ · (u∇K ∗ u) in R , for homogeneous potentials K = |x| , γ > 0. For γ > 2, the aggregation happens in infinite time and exhibits a concentration of mass along a collapsing δ-ring. We develop an asymptotic theory for the approach to this singular solution. For γ < 2, the solution blows up in finite time and we present careful numerics of second type similarity solutions for all γ in this range, including additional asymptotic behavior in the limits γ → 0 and γ → 2−.