Methods and Applications of Analysis

Volume 30 (2023)

Number 2

Sharp well-posedness and blowup results for parabolic systems of the Keller–Segel type

Pages: 53 – 76

DOI: https://dx.doi.org/10.4310/MAA.2023.v30.n2.a1

Authors

Piotr Biler (Instytut Matematyczny, Uniwersytet Wrocławski, Wrocław, Poland)

Alexandre Boritchev (Université Claude Bernard Lyon 1, ICJ UMR5208, CNRS, Ecole Centrale de Lyon, INSA Lyon, Université Jean Monnet, Villeurbanne, France)

Lorenzo Brandolese (Université Claude Bernard Lyon 1, ICJ UMR5208, CNRS, Ecole Centrale de Lyon, INSA Lyon, Université Jean Monnet, Villeurbanne, France)

Abstract

We study two toy models obtained after a slight modification of the nonlinearity of the usual doubly parabolic Keller–Segel system. For these toy models, both consisting of a system of two parabolic equations, we establish that for data which are, in a suitable sense, smaller than $\tau/(\ln \tau)^3$, where $\tau$ is the diffusion parameter in the equation for the chemo-attractant, we obtain global solutions. Moreover, for a class of data larger than $\tau$, we obtain the finite time blowup, in the whole space as well as in a bounded domain, with two different techniques. Thus, our analysis implies that our size condition on the initial data for the global existence of solutions is sharp, for large $\tau$, up to a logarithmic factor. These results show that global-in-time solutions can be obtained more easily with bigger diffusion coefficient $\tau$, similarly as is known for weaker nonlinear cross-diffusion terms compared to the strength of diffusion in the first equation.

Keywords

chemotaxis, cross-diffusion, Besov spaces, pseudo-measures, global-in-time solutions, blowup

2010 Mathematics Subject Classification

35B40, 35B44, 35K40, 35K55, 35Q92

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The first named author would like to thank Institut Camille Jordan, Université Claude Bernard-Lyon 1 for hospitality during his sabbatical stay (Sep 2021–Jan 2022) as a fellow of Institut des Études Avancées – Collegium de Lyon, partially supported by the Polish NCN grant 2016/23/B/ST1/00434.

The authors also gratefully acknowledge the support received by the ARQUS program.

Received 16 September 2022

Accepted 21 June 2023

Published 8 January 2024