InterPore2025

Effects of fluid inertia and variable-density flows on mineral dissolution: 3D Pore-scale simulations and millifluidics experiments

20 May 2025, 14:20

15m

Oral Presentation (MS03) Flow, transport and mechanics in fractured porous media MS03

Speaker

Hongfan Cao

Description

Mineral dissolution during groundwater flow is a crucial phenomenon that has received continued interest for decades as a main drive of various subsurface processes, such as carbon mineralization, karstification, and the formation of complex rock patterns in caves. In fractured media and dissolving porous media, fluid inertia can play an important role in shaping fluid flow and dissolution processes. For example, recent studies have reported that pore-scale vortical flows can readily occur, leading to mixing and reaction hotpots. Furthermore, as dissolution proceeds, the density of the fluid near solid fluid interfaces will increase and may lead to the density-driven convective flow. However, the effects of fluid inertia and density driven flows on mineral dissolution in fractured media have rarely been studied.

This study investigates the impact of fluid inertia and variable density flows on mineral dissolution in fractured media by combining visual laboratory experiments and three-dimensional (3D) pore-scale numerical simulations. A series of millifluidics experiments were conducted on a model single fracture/pore to examine how dissolution proceeds in the presence of inertial and density-driven convective flows. Gypsum cast from Plaster of Paris was utilized as the dissolving material in a polycarbonate flow channel. The flow channel was placed in a few different configurations, aligning the main channel flow with, perpendicular to, or against gravity, to examine the influence of changing the direction of density-driven flow with respect to the induced flow. Experiments are conducted at varying flow rates to investigate the effects of fluid inertia. To better understand the underlying mechanisms leading to different dissolution patterns, three-dimensional (3D) pore-scale numerical simulations with the same geometry used in the millifluidic experiments are performed. A micro-continuum formulation is used to numerically simulate pore-scale flow and reactive transport involving gypsum dissolution. Both the laboratory experiments and pore-scale numerical simulations indicate that the fluid inertia and density contrast resulting from dissolution can have major impacts on dissolution patterns and rates.