We are happy to have our most recent paper on infiltration dynamics in porous-fractured media published in Water Resources Research!
http://dx.doi.org/10.1029/2023WR036323
As part of his Ph.D. Florian has developed various laboratory experiments to study steady-state and transient infiltration processes in porous-fractured systems. While his former work has focused on larger scale network structures, his most recent work covers the detailed fracture-matrix interactions during infiltration events. In the study, a series of sophisticated laboratory experiments were conducted to analyze the flow dynamics, specifically focusing on the fluid penetration depth within fractures under different flow conditions. The experiments help to delineate various flow regimes that are either dominated by the fractures or the matrix, influenced by the rate of fluid flow. Florian meticulously compared the propagation of the wetting fronts within both the fractures and the matrix, and examined how these fronts interact with the lateral boundaries of the system.
Utilizing the analytical model developed by Nitao and Buscheck in 1991, our findings critically assess the impact of fracture-matrix interactions on fluid flow within fractured media. We discovered that the matrix imbibition significantly alters the observed flow characteristics in the fractures, which often behave like plug flow under conditions previously not considered under such flow patterns. Our results indicate that the model assumption of plug flow is not a necessary precondition for its applicability over a range of flow rates that exceed a critical threshold.
The study establishes three characteristic scaling regimes based on the state of matrix imbibition, showing a dynamic shift from fracture-dominated to matrix-dominated flow regimes as the flow rate increases. This transition points to a flow-rate-dependent limitation on the depth of fracture-dominated infiltration. While the scaling regimes are consistent with experimental observations at higher flow rates, at lower rates below the critical threshold, the model underestimates the initial penetration depth, leading to an immediate onset of the second flow regime and a delayed transition into the last phase.
While many questions remain the paper enhances our theoretical and practical understanding of how infiltration occurs in porous-fractured emedia, which is crucial for improving predictions in various geological and engineering applications. It also challenges and refines existing models, and helps to define future research topics to explore and better define the complexities of fluid flows in such complex systems.
WRR, Rüdiger et al. (2024)