A nonlocal convection–diffusion equation

In this paper we study a nonlocal equation that takes into account convective and diffusive effects, ut = J ∗ u − u + G ∗ (f (u)) − f (u) in Rd , with J radially symmetric and G not necessarily symmetric. First, we prove existence, uniqueness and continuous dependence with respect to the initial condition of solutions. This problem is the nonlocal analogous to the usual local convection–diffusion equation ut = u+ b · ∇(f (u)). In fact, we prove that solutions of the nonlocal equation converge to the solution of the usual convection–diffusion equation when we rescale the convolution kernels J and G appropriately. Finally we study the asymptotic behaviour of solutions as t→∞when f (u) = |u|q−1u withq >1.We find the decay rate and the first-order term in the asymptotic regime. © 2007 Elsevier Inc. All rights reserved