Effect of permeability heterogeneity on reactive convective dissolution

TL;DR

This study numerically investigates how different permeability heterogeneity patterns influence reactive buoyancy-driven convective dissolution, revealing that heterogeneity significantly affects flow dynamics, reaction rates, and mixing efficiency.

Contribution

It provides a comprehensive analysis of the effects of various permeability heterogeneity structures on reactive convection, highlighting the complex interactions and their impact on dissolution and mixing.

Findings

Vertically stratified and log-normal permeability fields enhance convective parameters.

Horizontal stratification impedes flow, reducing dissolution flux.

Shorter horizontal correlation length increases mixing efficiency.

Abstract

The impact of permeability heterogeneity on reactive buoyancy-driven convective dissolution is analyzed numerically in the case of a bimolecular A+B$\to$C reaction across varying Rayleigh numbers. The convective dynamics is compared in homogeneous, horizontally stratified, vertically stratified, and log-normally distributed permeability fields. Key variables, such as the total amount of product, mixing length, front position and width, reaction and scalar dissipation rates, and dissolution fluxes, are strongly influenced by the type of permeability heterogeneity. Vertically stratified and log-normally distributed permeability fields lead to larger values for all parameters compared to homogeneous fields. Horizontally stratified fields act as an obstacle to convective flow, resulting in slower front progression, thicker fingers, wider reaction fronts, and the lowest dissolution fluxes among all cases. When the reaction stabilizes convection, flow stagnation occurs near the extremum of the non-monotonic density profile, even in vertically stratified systems, highlighting the complex interaction between reactions and dissolution-driven convection. In log-normally distributed fields, the flow behavior depends on the permeability structure: smaller horizontal correlation lengths cause fingers to spread more horizontally, while larger horizontal correlation lengths promote more vertical movement with shorter wavelengths. Overall, a shorter horizontal correlation length relative to the vertical one leads to an increase in the value of all aforementioned parameters and thus to a more efficient mixing. These findings reveal how heterogeneity affects convective dynamics by influencing the reaction front, dissolution rates, mixing behavior, and mass transport efficiency, emphasizing the intricate role of permeability structure in reactive convective processes.