InterPore2026

Fluid Inertia and Geometry Effects on Mixing at Three-dimensional Fracture Intersections

19 May 2026, 15:05

1h 30m

Poster Presentation (MS08) Mixing, dispersion and reaction processes across scales in heterogeneous and fractured media Poster

Speaker

Jingxuan Deng

Description

Fracture intersections are potential hotspots for biogeochemical reactions because fluids with different properties can mix vigorously and react at these intersections. Although most existing studies assume purely viscous (Stokes) flow, many natural and engineered systems operate in a regime where inertial effects are non-negligible. Under such conditions, inertia can lead to complex three-dimensional (3D) flow structures and mixing behavior at intersections, yet a comprehensive understanding of the coupled effects of inertia, intersection geometry, and three-dimensional flow remains lacking.

In this study, we investigate mixing at 3D fracture intersections under laminar inertial conditions using microfluidic experiments with confocal laser scanning microscopy (CLSM), direct numerical simulations, and flow topology analysis. By systematically varying the Reynolds number and intersection geometry, we quantify how inertia-induced 3D flow structures influence mixing efficiency. We identify an optimal Reynolds number that maximizes mixing and show that this optimum depends strongly on intersection geometry. Flow topology analysis reveals that enhanced mixing is closely associated with inertia-induced stagnation points, flow separation, and recirculation zones. These topological features promote strong stretching and folding of solute interfaces, giving rise to localized mixing hot spots that dominate overall mixing behavior. At higher Reynolds numbers, mixing efficiency declines as advective transport increasingly dominates diffusion (high Péclet number) and the underlying flow topology no longer evolves, limiting further enhancement of interfacial deformation. To test the generality of our findings, we further examine the effects of inertia under uneven inflow conditions and in various rough intersection geometries. Together, these results elucidate quantitative relationships between flow topology and mixing at intersections and highlight the importance of accounting for inertial and three-dimensional effects when predicting transport and reactive processes in fractured media.