MATHEMATICAL ANALYSIS OF A REACTIVE-DIFFUSIVE MODEL OF THE DISPERSAL OF A CHEMICAL TRACER WITH NONLINEAR CONVECTION

Abstract

We formulate and analyze a nonlinear reaction-convection-diffusion system that models the dispersal of solutes, or chemical tracers, through a one-dimensional porous medium. A similar set of model equations also arises in a weakly nonlinear limit of the combustion equations. In particular, we address two fundamental questions with respect to the model system: first, the existence of wavefront type traveling wave solutions, and second, the local existence and uniqueness of solutions to the pure initial value problem. The solution to the wavefront problem is obtained by showing the existence of a heteroclinic orbit in a two-dimensional phase space. The existence argument for the initial value problem is based on the contraction mapping theorem and Sobolev embedding. In the final section we prove non-negativity of the solution.