“…The concept of the double-porosity was developed in early 1960s for modelling the flow of a single component in a single phase within a naturally fractured reservoir (see, for example, [13]). Later, the concept has been applied to water transport in dolostones [14,15], ionic transport in soils [16], ionic solution flow in fractured rocks [17], modelling of groundwater flow [18], modelling of waste and contaminant transport in soils [19,20], modelling of fluid flow in pavement [21], modelling of chloride penetration in concrete [12], investigation of interaction between ordinary Portland cement and opalinus clay [22], and study of the characteristic behaviour of a permeable medium containing regions which contribute significantly to the pore volume of the system but negligibly to the flow capacity [23]. The mathematical derivation of the double-porosity model for general porous materials was provided in references [24,25].…”