Calculation of medicine diffusion coefficient out of three-dimensional chitosan film

The diffusion coefficient of medicine out of chitosan film with finite dimensions is calculated. To fit the experimental data it is assumed that the diffusion coefficient is exponentially decreasing function of time. Analytical solution of direct problem is obtained by variables separation. Based on it, unknown values describing diffusion are found by least-squares method. The calculated fit is tested numerically by using ANSYS package. The comparison between diffusion coefficients for one-dimensional and three-dimensional films is made. It is shown that for three-dimensional film diffusion coefficient decreases compared with one-dimensional film, but the quality of fit stays almost unchanged for films with different numbers of dimensions.