Finite-Time Blow-up in a Two-Species Chemotaxis-Competition Model with Degenerate Diffusion.

This paper is concerned with the two-species chemotaxis-competition model with degenerate diffusion, { u t = Δ u m 1 − χ 1 ∇ ⋅ (u ∇ w) + μ 1 u (1 − u − a 1 v) , x ∈ Ω , t > 0 , v t = Δ v m 2 − χ 2 ∇ ⋅ (v ∇ w) + μ 2 v (1 − a 2 u − v) , x ∈ Ω , t > 0 , 0 = Δ w + u + v − M ‾ (t) , x ∈ Ω , t > 0 , with ∫ Ω w (x , t) d x = 0 , t > 0 , where Ω : = B R (0) ⊂ R n (n ≥ 5) is a ball with some R > 0 ; m 1 , m 2 > 1 , χ 1 , χ 2 , μ 1 , μ 2 , a 1 , a 2 > 0 ; M ‾ (t) is the spatial average of u + v . In this paper, we show that if m 1 < 2 − 4 n , χ 1 > n (2 − m 1) n (2 − m 1) − 4 ⋅ max { 1 , a 1 } μ 1 and χ 2 > μ 2 a 2 or m 2 < 2 − 4 n , χ 1 > μ 1 a 1 and χ 2 > n (2 − m 2) n (2 − m 2) − 4 ⋅ max { 1 , a 2 } μ 2 , then there exist radially symmetric initial data such that the weak solution blows up in finite time in the sense that there is T ˜ max ∈ (0 , ∞) such that lim sup t ↗ T ˜ max (∥ u (t) ∥ L ∞ (Ω) + ∥ v (t) ∥ L ∞ (Ω)) = ∞. To obtain this result, we apply the method in the previous paper (Discrete Contin. Dyn. Syst., Ser. B 28(1):262–286, 2023) to derive an integral inequality for a moment-type functional, which was introduced by Winkler (Z. Angew. Math. Phys. 69(2):69, 2018). Moreover, before proving blow-up of solutions in the above model, we give a result on finite-time blow-up under the same conditions for m 1 , m 2 , χ 1 and χ 2 in the model with the terms Δ u m 1 , Δ v m 2 replaced with the nondegenerate diffusion terms Δ (u + ε) m 1 , Δ (v + ε) m 2 , where ε ∈ (0 , 1 ] . [ABSTRACT FROM AUTHOR]