Non-Fickian solute transport in three-dimensional crossed shear rock fractures at different contact ratios

Solute transport in fractured rocks plays a crucial role in many subsurface processes, such as geothermal resource extraction and carbon capture and storage. This study conducted simulations of non-Fickian solute transport at varying contact ratios and voids in crossed shear fractures. Results indicated that increasing the contact ratio of the crossed fractures intensified the "tailing" phenomenon of non-Fickian solute transport, and has a negative relationship with the solute outflow concentration. Additionally, the anisotropy of intersections and the variations in their void structure both influence the redistribution and mixing of fluid and solute, therefore, we propose a method to determine the solute mixing patterns at the intersection. Ultimately, while the volume and magnitude of the separated vortex domain in the flow field can influence the non-Fickian solute transport, the "tailing" phenomenon is more significantly affected by its magnitude.