“…Analytical approaches have generally been concerned with one-dimensional, planar interface, time-dependent models, or higher-dimensional, steady-state models. To solve the problems in the former category, recent investigations have used series expansion [4], similarity solution [6,8], Laplace transform [7], and Green's function techniques [5]. Quasi-steady models [2,3] have also been used by employing perturbation expansions in powers of a small parameter, which is inversely proportional to the latent heat, and small in magnitude due to the relatively large value of the latent heat.…”