Mathematical modelling of sorption processes in timber, based on numerical analysis

Although moisture is a leading cause of degradation in a range of building materials the transport mechanisms for adsorption and desorption are not well understood and mathematical modelling has been of limited success. This paper presents a mathematical model with numerical analysis by use of the method of finite differences. Mathematical analysis of moisture transmission with assumption of Newmann's boundary conditions was made. The model can be used to describe the process of adsorption and desorption of moisture in timber, where the transport of moisture follows the transverse direction of wood, with potential extension to the longitudinal direction also. The model makes it possible to attain the profiles of concentration of moisture developed throughout the sample. Data resulting from changes in relative humidity and collected by continuous monitoring by calibrated moisture sensors are compared against result from modeling. Good agreement has been observed over various conditions.