Transient simulation of coupled heat and moisture flow through a multi-layer porous solid exposed to solar heat flux

The integral equations are discretized using mixed-boundary elements and a multidomain method also known as the macro-elements technique (Brebbia, 1984 [1], Popov et al., 2007 [2]). The numerical model uses quadratic approximation over space and linear approximation over time for all field functions, which provides highly accurate numerical results.