A lattice Boltzmann approach for modeling coupled evaporation/precipitation processes in porous media

We present a novel numerical approach for simulating coupled evaporation and salt precipitation processes in porous media using the lattice Boltzmann method. Our model combines a Shan-Chen multiphase flow framework with a volume-based discretization method for diffusing salt species, where the coupling mechanism operates through solvation energy differences. The framework incorporates a precipitation model based on first-order reaction kinetics, enabling the transformation of fluid cells into solid crystal cells upon reaching threshold concentrations. We verify our model against analytical solutions for crystal growth and evaporation rates, demonstrating excellent agreement. The model is then applied to investigate the influence of wetting properties on evaporation and salt precipitation in porous media. Our simulations reveal that the wettability of both the porous medium and the precipitated salt crystals has a significant impact on precipitation patterns and pore clogging. Notably, increased salt crystal wettability promotes more effective pore blocking, substantially reducing permeability and evaporation rates. We find that the slowest evaporation occurs when salt crystals have high wettability, while the porous medium exhibits lower wettability because this configuration maximizes pore clogging. This work presents a novel framework to gain insight into the intricate interplay between fluid dynamics, wetting properties, and salt precipitation in porous media, with implications for understanding soil salinization, building material degradation, and the formation of geological salt crusts.