Numerical modeling of 2D hygro-thermal transport in unsaturated concrete with capillary suction

In this study, the importance of capillary suction was emphasized through its implementation in a hygrothermal transport model used to predict water transport in ordinary concrete. In the model, heat transfer is described by the classical Fourier equation. In addition, the homogeneous vapor diffusion is modeled using a gradient-driven Fick's law, and the local kinematics of the liquid capillary flow are illustrated by a pressure-driven Darcy's law. Mathematical operations were performed to obtain a combined governing equation for water transport, but with different transport coefficient expressions under different circumstances. The complete hygrothermal transport model was discretized in a 2D finite element program (TransChlor2D) and solved using an explicit and one-way coupling scheme. Experimental methods and analytical formulas were used to assess the hygrothermal transport parameters, and the model was validated with various durability tests, demonstrating its ability to capture the impact of capillary flow on water content profiles.