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The influence of angle patterns of intersecting fractures is crucial for a profound understanding of the flow characteristic of fractured rock masses. This study employs hydraulic and visualization experiments to investigate macroscopic nonlinear flow behavior and local flow field characteristics of a "one inlet two outlet" fracture intersection with varying angle patterns. The angle pattern exerts a significant influence on the morphology of the intersection, leading to enhanced nonlinear flow and altered flow rate distribution. Both the nonlinear coefficient (b) and the ratio of flow rate distribution (ɛ) exhibit a Gaussian distribution pattern with respect to the angle patterns. By observing the intersection morphology and local flow fields under different angle patterns, it was found that the protrusion caused by the inlet and outlet fractures significantly impacts the fluid flow entering the outlet fractures, particularly under high Reynolds number (Re) conditions. Using a machine learning algorithm based on neural networks, the flow rate distribution at the outlet of the intersection fracture under different Re values and angle patterns is predicted. The model demonstrated accurate predictions of the outlet flow rate distribution for intersection fractures under diverse conditions. Additionally, by analyzing the flow velocity and flow characteristics at different positions within the intersection, the relationship between the macroscopic flow rate distribution and the flow field characteristics at the intersection has been clarified. These results will aid in the study of groundwater flow behavior, fluid flow in microfluidic chips, and seepage heat transfer. [ABSTRACT FROM AUTHOR]

An understanding of the influence of fracture surface roughness on local flow patterns is critical for underground engineering and geological sciences. The flow pattern in a fracture is not only affected by the large-scale waviness of the fracture morphology, but also by the local small-scale roughness of the fracture surface, in particular the local flow pattern. The microfluidic field of flow in two fracture models with and without local small-scale roughness was investigated through a microscopic visualization hydraulic experiment. By quantitatively analyzing the velocity and vorticity in the two fracture models, the results indicate that the characteristics of the fracture microfluidic field are closely related to the local small-scale roughness. First, due to the effect of the local small-scale roughness, it is easier to generate and develop eddies in the original fractures that contain small-scale roughness. Meanwhile, the local small-scale roughness increases the velocity gradient in the vertical section of the fracture flow and further enhances the complexity of the fracture flow field. Moreover, although the small-scale roughness has little impact on the position of the maximum velocity, the area of eddies increases and the effective flow aperture is significantly reduced. [ABSTRACT FROM AUTHOR]