A hybrid variational principle for the Keller-Segel system in R2

Abstract

We construct weak global in time solutions to the classical Keller-Segel system describing cell movement by chemotaxis in two dimensions when the total mass is below the established critical value. Our construction takes advantage of the fact that the Keller-Segel system can be realized as a gradient flow in a suitable functional product space. This allows us to employ a hybrid variational principle which is a generalisation of the minimizing implicit scheme for Wasserstein distances introduced by [R. Jordan, D. Kinderlehrer and F. Otto, SIAM J. Math. Anal. 29 (1998) 1-17].