On some sharper boundedness conditions in the higher-dimensional chemotaxis-consumption model

Abstract

For the classical zero-flux chemotaxis-consumption model \begin{equation*} u_t= \Delta u - \chi \nabla \cdot (u \nabla v) \quad \textrm{and}\quad v_t=\Delta v- uv, \quad \text{ with } (x,t)\in \Omega \times (0,T_{max}), \end{equation*} $\Omega$ being a bounded and smooth domain of $\mathbb{R}^n$, $n\geq 3$, $\chi$ some positive number and $T_{max} \in (0,\infty]$, the following was established in a paper by Tao: for every sufficiently regular initial data $u(x,0)=u_0(x)\geq 0$ and $v(x,0)=v_0(x) \geq 0$, there is $\chi(\lVert v_0 \rVert_{L^\infty(\Omega)})$ such that for all $0<\chi\leq \chi(\lVert v_0 \rVert_{L^\infty(\Omega)})$, the initial-boundary value problem has a unique classical solution in $\Omega \times (0,\infty)$ which is bounded. In this paper, whenever $n\geq 5$, we obtain the same claim for larger values of the constant $\chi(\|v_0\|_{L^{\infty}(\Omega)})$.