Modeling wicking in textiles using the dual porosity approach

We develop a dual porosity diffusivity model to simulate the complex dynamic wicking behavior in textiles: wicking inside yarns coupled with wicking in the voids in between the yarns. The model expands the Richards equation to account for mass exchange between the two pore systems. This exchange, however, appears to be very small for cotton textiles and the system appears to behave as two parallel pore systems. The water uptake in the yarn pore system is mostly affected by the textile structure (woven versus knit), while the void pore system differs in the maximum moisture content that can be achieved during uptake. Gravity is shown to play an important role, especially for the coarser void pore system.