A CLASS OF MOVING BOUNDARY-PROBLEMS ARISING IN DRYING PROCESSES

Various representations of equilibrium drying processes are presented in a coherent framework as a class of moving boundary value problems involving the hysteresis phenomenon. The class splits into two subclasses of problems, called here implicit models and jump models; individual problems are categorized as sorption models, wet and dry models, and hysteresis-jump models. The mathematical model for the evolution of moisture, humidity, temperature, and pressure consists of a strongly coupled system of quasilinear partial differential equations, which is parabolic in the physical domain, together with the associated jump conditions of the Rankine-Hugoniot type. Whereas previous work on these models dealt with the numerical results, the present study addresses the mathematical wellposedness of the problems. The wet and dry jump model for a slab is stated, in both the classical and the weak formulations. Some results on local existence and uniqueness are obtained by using existing theory and the embedding technique.