Finite-time blow-up in a quasilinear two-species chemotaxis system with two chemicals

TL;DR

This paper studies conditions under which a two-species chemotaxis system with nonlinear diffusion exhibits finite-time blow-up, complementing previous results on boundedness and extending understanding of chemotactic pattern formation.

Contribution

It establishes finite-time blow-up criteria for a quasilinear two-species chemotaxis system with two chemicals, expanding the theoretical understanding beyond classical boundedness conditions.

Findings

Finite-time blow-up occurs when the sum of diffusion exponents exceeds a certain threshold.

The results complement previous boundedness conditions, providing a complete picture of solution behavior.

The analysis applies to systems with nonlinear diffusion functions of specific growth rates.

Abstract

This paper investigates the finite-time blow-up phenomena to a quasilinear two-species chemotaxis system with two chemicals \begin{align}\tag{$\star$} \begin{cases} u_t = \nabla \cdot \left(D_1(u) \nabla u\right) - \nabla \cdot \left(u \nabla v\right), & x \in \Omega, \ t > 0, 0 = \Delta v - \mu_2 + w, \quad \mu_2=\fint_{\Omega}w, & x \in \Omega, \ t > 0, w_t = \nabla \cdot \left(D_2(w) \nabla w\right) - \nabla \cdot \left(w \nabla z\right), & x \in \Omega, \ t > 0, 0 = \Delta z - \mu_1 + u, \quad \mu_1=\fint_{\Omega}u, & x \in \Omega, \ t > 0, \frac{\partial u}{\partial \nu} = \frac{\partial v}{\partial \nu} = \frac{\partial w}{\partial \nu} = \frac{\partial z}{\partial \nu} = 0, & x \in \partial \Omega, \ t > 0, u(x, 0) = u_0(x), \quad w(x, 0) = w_0(x), & x \in \Omega, \end{cases} \end{align} where $\Omega \subset \mathbb{R}^n$ $(n \geqslant 3)$ is a smoothly bounded domain. The nonlinear diffusion functions \( D_1(s) \) and \( D_2(s) \) are of the following forms: \begin{align*} D_1(s)\simeq s^{m_1-1} \quad \text{and}\quad D_2(s) \simeq s^{m_2-1}, \quad m_1,m_2> 1 \end{align*} for $s\geqslant 1$. For the classical two-species chemotaxis system with two chemicals (i.e. the second and fourth equations are replaced by $0 = \Delta v - v + w$ and $0 = \Delta z - z + u$ ), Zhong [J. Math. Anal. Appl., 500 (2021), Paper No. 125130, pp. 22.] showed that the system possesses a globally bounded classical solution in the case that \[ m_1 + m_2 < \max\left\{m_1m_2 + \frac{2m_1}{ n},\ m_1m_2 + \frac{2m_2 }{ n}\right\}. \] Complementing the boundedness result, we prove that the system ($\star$) admits solutions that blow up in finite time, if \[ m_1 + m_2 > \max\left\{ m_1m_2 + \frac{2m_1}{ n},\ m_1m_2 + \frac{2m_2}{ n}\right\} \] with $n\geqslant 3$.