A numerical method for determination of moisture transfer coefficient according to the diffusion moisture profiles

Abstract

For a set of the measured diffusion moisture profiles, a numerical method for determination of moisture transfer coefficient D(w, t) is suggested. The transfer coefficient is found as a sum of the degree $p_0 w^{p(t)}$ and exponential $Ae^{\mu (w - v_0 )}$ functions of the moisture concentration w, as opposite to the previous works. The exponent p(t) of the power function depends on time t. The exponential function describes profiles for large times nearby the boundary of the sample, where the moisture evaporation takes place to the atmosphere. A conservative difference scheme for numerical solution of direct problem is suggested. An inverse problem for minimization of an error functional is solved by the Newton method. Thus, a more accurate coincidence of the calculated profiles of the moisture concentration to the measured profiles is gained.