On convergence to steady state of solutions of parabolic equations in unbounded domains

Solutions of the first mixed boundary value problem for a class of parabolic partial differential equations are shown to converge to solutions of associated elliptic boundary value problems as time t → ∞. The method of proof involves the introduction, for the parabolic problem, of a class of generalized solutions which may behave asymptotically, at spatial infinity, like solutions of the associated elliptic equation.