On the global existence of solutions to an aggregation model

In this paper we consider a reaction–diffusion–chemotaxis aggregation model of Keller–Segel type with a nonlinear, degenerate diffusion. Assuming that the diffusion function f(n) takes values sufficiently large, i.e. takes values greater than the values of a power function with sufficiently high power (f(n)⩾δnp for all n>0, where δ>0 is a constant), we prove global-in-time existence of weak solutions. Since one of the main features of Keller–Segel type models is the possibility of blow-up of solutions in finite time, we will derive the uniform-in-time boundedness, which prevents the explosion of solutions. The uniqueness of solutions is proved provided that some higher regularity condition on solutions is known a priori. Finally, computational simulation results showing the effect of three different types of diffusion function are presented.