“…Moving boundary problems occur in many physical applications involving diffusion, such as in heat transfer where a phase transition occurs, in moisture transport such as swelling grains or polymers, and in deformable porous media problems where the solid displacement is governed by diffusion (see, for example, [19,3,22,6,5]). Cavalcanti et al [7] worked with a time-dependent function a = a t, Ωt |∇u(x, t)| 2 dx to establish the solvability and exponential energy decay of the solution for a model given by a hyperbolic-parabolic equation in an open bounded subset of R n , with moving boundary.…”