Analysis of SIR Reaction diffusion system with constant birth and death rate

This is a truncation of the second year group project at Imperial college london. In this paper, we consider a semilinear reaction diffusion system of SIR model which involves the birth rate and the death rate. We first prove the non-negativity and global existence theorem to ensure that the model makes sense. We prove the uniform convergence of the infection-free solution and study an example that separable solutions can be computed. We also focus on the steady state solution, which we prove the non-uniqueness of the solution and investigate the regularity of the general solution. In the end we also introduce an interesting phenomenon, which is called the Turing instability caused by the diffusion in the model.