## African Diaspora Journal of Mathematics

- Afr. Diaspora J. Math. (N.S.)
- Volume 21, Number 1 (2018), 1-31.

### Semigroup and Blow-Up Dynamics of Attraction Keller-Segel Equations in Scale of Banach Spaces

David S. I. Iiyambo and Robert Willie

#### Abstract

In this paper, we study the asymptotic and blow-up dynamics of the attraction Keller-Segel chemotaxis system of equations in scale of Banach spaces $E^\alpha_q = H^{2\alpha,q}(\Omega), −1 \le \alpha \le 1,1 \lt q \lt \infty$, where $\Omega \subset \mathbb{R}^N$ is a bounded spatial domain. We show that the system of equations is well-posed for a perturbed analytic semigroup, whenever $2\chi + a \lt \left( \frac{Ne\pi}{2} \right)^{\beta+\frac{\gamma}{2}-\frac{1}{2}}$, where $\chi$ is the chemical attractivity coefficient, $a$ is the rate of production of chemical, and $q, \beta, \gamma$ are of the scale spaces. Thus, as $t\nearrow\infty$, the asymptotic dynamics are captured in the limit set $\mathcal{M}\cup \{0\}$, where $\mathcal{M} = |\Omega|L^1 -$spatial average solutions. The constants for the sharp space embedding $E^\alpha_q \subset L ^\Theta(\Omega) (1\lt\Theta\le\infty)$ indicate that for either the application of Banach fixed point theorem, or the global existence of solutions, no need of either the time for a contraction mapping, nor the initial data of the system of equations, to be small, respectively. In blow-up dynamics, we prove that the solutions blow-up at the borderline scale spaces $E^\alpha_q, \alpha = \frac{N}{2q}$, independent of time $t > 0$, if the chemo-attractivity coefficient dominates the Moser-Trudinger threshold value. An analysis of the finite time bounds for blow-up of solutions in norm of $L^{2p}(\Omega),1 \le p \le 6$ and $\Omega \subset \mathbb{R}^N,N = 2, 3$, is also furnished.

#### Article information

**Source**

Afr. Diaspora J. Math. (N.S.), Volume 21, Number 1 (2018), 1-31.

**Dates**

First available in Project Euclid: 7 March 2018

**Permanent link to this document**

https://projecteuclid.org/euclid.adjm/1520391703

**Mathematical Reviews number (MathSciNet)**

MR3763735

**Zentralblatt MATH identifier**

06873705

**Subjects**

Primary: 35B40-4 35K50 35K57: Reaction-diffusion equations

**Keywords**

Keller-Segel model chemotaxis asymptotic dynamics blow-up analysis

#### Citation

Iiyambo, David S. I.; Willie, Robert. Semigroup and Blow-Up Dynamics of Attraction Keller-Segel Equations in Scale of Banach Spaces. Afr. Diaspora J. Math. (N.S.) 21 (2018), no. 1, 1--31. https://projecteuclid.org/euclid.adjm/1520391703