Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
CONVECTIVE PATTERNS IN HELE-SHAW FLOWS DRIVEN BY DENSITY GRADIENTS AND CHEMICAL COMPOSITION CHANGES
Submission Author:
Bernardo Alberto Marcussi , RJ
Co-Authors:
Bernardo Alberto Marcussi, André Celestino Martins, Rachel Manhães de Lucena, Norberto Mangiavacchi
Presenter: Bernardo Alberto Marcussi
doi://10.26678/ABCM.COBEM2023.COB2023-1519
Abstract
The phenomenon of fluid displacement in porous media is of great practical interest for a variety of geophysical and environmental applications, such as Carbon Capture and Storage (CCS), oil recovery, water contamination, and granular flows, however studying this phenomenon in situ is extremely challenging. During displacement, convective flow patterns known as fingering have been observed and studied using the Hele-Shaw cell, an experimental device which replicates the porous media flow conditions found in nature, and may be used as a benchmarking tool for theoretical models and numerical simulations of fluid flow patterns against experimental data. The fluid flow behaviour in porous media can be explained by applying Darcy’s law, provided that the solute hydrodynamic dispersion effect in the cell is taken into account. This study involved the assembly of a Hele-Shaw cell to investigate the formation of flow patterns with fingering instability in density-driven flows in porous media generated by changes in chemical composition of the fluid medium. The cell consisted of two rectangular plates, separated by seals and enclosing impermeable boundaries and an adjustable, uniform gap. Only the upper boundary of the cell was left open, where concentration gradients were generated and resulted in density gradients in the aqueous phase. Following an initial diffusive phase, the layer of heavy mixture thickened and developed instability, leading to the formation of finger-like structures. The flow evolution was recorded using a camera while the Hele-Shaw cell was illuminated from the backside with an array of LED lamps. The problem was characterised by three dimensionless parameters which determined the flow regime between the plates. The average flow velocity during the experiments was calculated and found to align with previous estimates derived from the HeleShaw equation. Furthermore, estimates of the concentration field and its derivative with respect to the width dimension of the cell were obtained. The vorticity of the fluid, in the axis across the gap dimension, was also computed, and the stream function was determined by solving a Poisson equation. Finally, the velocity components in both the vertical and horizontal directions were computed. This study utilised a Hele-Shaw cell to replicate the two-dimensional fluid flow behaviour in porous media, recovering the significant role played by solute hydrodynamic dispersion, and providing valuable insights into the dynamic structures of gravity-driven porous media flows.
Keywords
Porous media, Hele-Shaw cell, fingering instability
