Recently, Landman, Pel and Kaasschieter proposed an analytic solution for a non-linear drying problem using a quasi-steady state solution. This analytic model for drying is explained here. An important consequence of this model is that the drying front has a constant speed when it is entering the material. This is also observed in experiments. On the basis of this constant drying front speed comparisons are made between the analytic model and numerical simulations. Finally comparisons are made between measured moisture profiles during drying and the analytic model.
Pel, L., Landman, K. A., & Kaasschieter, E. F. (2002). Analytic solution for the non-linear drying problem. International Journal of Heat and Mass Transfer, 45(15), 3173-3180. https://doi.org/10.1016/S0017-9310(02)00025-X