Rotating spirals for three-component competition systems

Abstract

We investigate the existence of rotating spirals for three-component competition-diffusion systems in $B_1\subset \mathbb{R}^2$: \begin{equation*} \begin{cases} \partial_tu_1-\Delta u_1=f(u_1)-\beta \alpha u_1u_2-\beta \gamma u_1 u_3,& \text{in}\ B_1\times \mathbb{R}^+, \partial_tu_2-\Delta u_2=f(u_2)-\beta \gamma u_1u_2-\beta \alpha u_2 u_3,& \text{in}\ B_1\times \mathbb{R}^+, \partial_tu_3-\Delta u_3=f(u_3)-\beta \alpha u_1u_3-\beta \gamma u_2 u_3,& \text{in}\ B_1\times \mathbb{R}^+, u_i(\textbf{x},0)=u_{i,0}(\textbf{x}), i=1,2,3, &\text{in} \ B_1, \end{cases} \end{equation*} with Neumann or Dirichlet boundary conditions, where $f(s)=\mu s(1-s)$, $\mu, \beta>0$, $\alpha>\gamma>0$. For the Neumann problem, we establish the existence of rotating spirals by applying the multi-parameter bifurcation theorem. As a byproduct, the instability of the constant positive solution is proved. In addition, for the non-homogeneous Dirichlet problem, the Rothe fixed point theorem is employed to prove the existence of rotating spirals.