Pore-scale numerical investigation of the impacts of surface roughness: Upscaling of reaction rates in rough fractures
Abstract
The roughness of solid surfaces influences mineral dissolution rates by affecting flow and transport in the near-surface regions and by increasing the surface area available for reaction. The impact of surface area is commonly accounted for by using the surface roughness factor (SRF), which is the ratio between the total surface area and the nominal or geometric surface area. The coupled impacts of hydrodynamics and transport, however, are rarely considered. In this study, we performed pore-scale reactive transport simulations in a series of synthetic 2D rough fractures to investigate the compound effects of surface roughness on the reaction rates in fractures. Simulation results show that while reaction rates increase with SRF, the increase is not linearly proportional to that of the surface area. Rather, local concentration gradients resulting from flow and transport processes limit the increase in the rate. In addition, surface roughness gives rise to concentration gradients that do not otherwise develop in the flat-surface geometries typically considered in modeling studies. To describe the impacts of the surface area increase on reaction rate at different roughness and flow velocities, three distinct regimes were identified. A unified mathematical relationship was also developed that allows the reaction rate in a roughmore »
- Authors:
- Publication Date:
- Research Org.:
- Energy Frontier Research Centers (EFRC) (United States). Center for Nanoscale Control of Geologic CO2 (NCGC); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE National Nuclear Security Administration (NNSA)
- OSTI Identifier:
- 1724304
- Alternate Identifier(s):
- OSTI ID: 1477408
- Grant/Contract Number:
- AC02-05CH11231; 17-SC-20-SC
- Resource Type:
- Published Article
- Journal Name:
- Geochimica et Cosmochimica Acta
- Additional Journal Information:
- Journal Name: Geochimica et Cosmochimica Acta Journal Volume: 239 Journal Issue: C; Journal ID: ISSN 0016-7037
- Publisher:
- Elsevier
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 36 MATERIALS SCIENCE; Surface roughness; Reaction rate; Upscaling; Fracture; Pore-scale reactive transport model
Citation Formats
Deng, Hang, Molins, Sergi, Trebotich, David, Steefel, Carl, and DePaolo, Donald. Pore-scale numerical investigation of the impacts of surface roughness: Upscaling of reaction rates in rough fractures. United States: N. p., 2018.
Web. doi:10.1016/j.gca.2018.08.005.
Deng, Hang, Molins, Sergi, Trebotich, David, Steefel, Carl, & DePaolo, Donald. Pore-scale numerical investigation of the impacts of surface roughness: Upscaling of reaction rates in rough fractures. United States. https://doi.org/10.1016/j.gca.2018.08.005
Deng, Hang, Molins, Sergi, Trebotich, David, Steefel, Carl, and DePaolo, Donald. Mon .
"Pore-scale numerical investigation of the impacts of surface roughness: Upscaling of reaction rates in rough fractures". United States. https://doi.org/10.1016/j.gca.2018.08.005.
@article{osti_1724304,
title = {Pore-scale numerical investigation of the impacts of surface roughness: Upscaling of reaction rates in rough fractures},
author = {Deng, Hang and Molins, Sergi and Trebotich, David and Steefel, Carl and DePaolo, Donald},
abstractNote = {The roughness of solid surfaces influences mineral dissolution rates by affecting flow and transport in the near-surface regions and by increasing the surface area available for reaction. The impact of surface area is commonly accounted for by using the surface roughness factor (SRF), which is the ratio between the total surface area and the nominal or geometric surface area. The coupled impacts of hydrodynamics and transport, however, are rarely considered. In this study, we performed pore-scale reactive transport simulations in a series of synthetic 2D rough fractures to investigate the compound effects of surface roughness on the reaction rates in fractures. Simulation results show that while reaction rates increase with SRF, the increase is not linearly proportional to that of the surface area. Rather, local concentration gradients resulting from flow and transport processes limit the increase in the rate. In addition, surface roughness gives rise to concentration gradients that do not otherwise develop in the flat-surface geometries typically considered in modeling studies. To describe the impacts of the surface area increase on reaction rate at different roughness and flow velocities, three distinct regimes were identified. A unified mathematical relationship was also developed that allows the reaction rate in a rough fracture to be approximated by the well-mixed reactor reaction rate and a correction factor. The correction factor follows a power-law function of SRF, with the multiplying factor and exponent expressed as exponential functions of the Péclet and Damköhler number. This mathematical formulation provides a valuable upscaling approach for effective integration of sub-grid scale surface roughness in larger scale continuum models.},
doi = {10.1016/j.gca.2018.08.005},
journal = {Geochimica et Cosmochimica Acta},
number = C,
volume = 239,
place = {United States},
year = {Mon Oct 01 00:00:00 EDT 2018},
month = {Mon Oct 01 00:00:00 EDT 2018}
}
https://doi.org/10.1016/j.gca.2018.08.005
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Works referencing / citing this record:
Simulation of mineral dissolution at the pore scale with evolving fluid-solid interfaces: review of approaches and benchmark problem set
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- Molins, Sergi; Soulaine, Cyprien; Prasianakis, Nikolaos I.
- Computational Geosciences
Characterizing the Impact of Fractured Caprock Heterogeneity on Supercritical CO$$_2$$ Injection
journal, November 2019
- Hyman, Jeffrey D.; Jiménez-Martínez, Joaquin; Gable, Carl W.
- Transport in Porous Media, Vol. 131, Issue 3