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Title: Pore-scale water dynamics during drying and the impacts of structure and surface wettability

Plants and microbes secrete mucilage into soil during dry conditions, which can alter soil structure and increase contact angle. Structured soils exhibit a broad pore size distribution with many small and many large pores, and strong capillary forces in narrow pores can retain moisture in soil aggregates. Meanwhile, contact angle determines the water repellency of soils, which can result in suppressed evaporation rates. Although they are often studied independently, both structure and contact angle influence water movement, distribution, and retention in soils. Here drying experiments were conducted using soil micromodels patterned to emulate different aggregation states of a sandy loam soil. Micromodels were treated to exhibit contact angles representative of those in bulk soil (8.4° ± 1.9°) and the rhizosphere (65° ± 9.2°). Drying was simulated using a lattice Boltzmann single-component, multiphase model. In our experiments, micromodels with higher contact angle surfaces took 4 times longer to completely dry versus micromodels with lower contact angle surfaces. Microstructure influenced drying rate as a function of saturation and controlled the spatial distribution of moisture within micromodels. In conclusion, lattice Boltzmann simulations accurately predicted pore-scale moisture retention patterns within micromodels with different structures and contact angles.
Authors:
ORCiD logo [1] ;  [2] ;  [3] ;  [3] ;  [2] ;  [2] ;  [4] ;  [3] ; ORCiD logo [5]
  1. Univ. of Connecticut, Storrs, CT (United States). Dept. of Civil and Environmental Engineering
  2. Benedict College, Columbia SC (United States). Dept. of Physics and Engineering
  3. Univ. of Connecticut, Storrs, CT (United States). Dept. of Chemical and Biomolecular Engineering
  4. Univ. of Connecticut, Storrs, CT (United States). Dept. of Molecular and Cell Biology
  5. Univ. of Connecticut, Storrs, CT (United States). Dept. of Chemical and Biomolecular Engineering, and Center for Environmental Sciences and Engineering
Publication Date:
Grant/Contract Number:
SC0014522; 2012-67020-19380
Type:
Accepted Manuscript
Journal Name:
Water Resources Research
Additional Journal Information:
Journal Volume: 53; Journal Issue: 7; Journal ID: ISSN 0043-1397
Publisher:
American Geophysical Union (AGU)
Research Org:
Univ. of Connecticut, Storrs, CT (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; lattice Boltzmann method; unsaturated; contact angle; soil structure; microfluidic
OSTI Identifier:
1474400
Alternate Identifier(s):
OSTI ID: 1375527

Cruz, Brian C., Furrer, Jessica M., Guo, Yi-Syuan, Dougherty, Daniel, Hinestroza, Hector F., Hernandez, Jhoan S., Gage, Daniel J., Cho, Yong Ku, and Shor, Leslie M.. Pore-scale water dynamics during drying and the impacts of structure and surface wettability. United States: N. p., Web. doi:10.1002/2016WR019862.
Cruz, Brian C., Furrer, Jessica M., Guo, Yi-Syuan, Dougherty, Daniel, Hinestroza, Hector F., Hernandez, Jhoan S., Gage, Daniel J., Cho, Yong Ku, & Shor, Leslie M.. Pore-scale water dynamics during drying and the impacts of structure and surface wettability. United States. doi:10.1002/2016WR019862.
Cruz, Brian C., Furrer, Jessica M., Guo, Yi-Syuan, Dougherty, Daniel, Hinestroza, Hector F., Hernandez, Jhoan S., Gage, Daniel J., Cho, Yong Ku, and Shor, Leslie M.. 2017. "Pore-scale water dynamics during drying and the impacts of structure and surface wettability". United States. doi:10.1002/2016WR019862. https://www.osti.gov/servlets/purl/1474400.
@article{osti_1474400,
title = {Pore-scale water dynamics during drying and the impacts of structure and surface wettability},
author = {Cruz, Brian C. and Furrer, Jessica M. and Guo, Yi-Syuan and Dougherty, Daniel and Hinestroza, Hector F. and Hernandez, Jhoan S. and Gage, Daniel J. and Cho, Yong Ku and Shor, Leslie M.},
abstractNote = {Plants and microbes secrete mucilage into soil during dry conditions, which can alter soil structure and increase contact angle. Structured soils exhibit a broad pore size distribution with many small and many large pores, and strong capillary forces in narrow pores can retain moisture in soil aggregates. Meanwhile, contact angle determines the water repellency of soils, which can result in suppressed evaporation rates. Although they are often studied independently, both structure and contact angle influence water movement, distribution, and retention in soils. Here drying experiments were conducted using soil micromodels patterned to emulate different aggregation states of a sandy loam soil. Micromodels were treated to exhibit contact angles representative of those in bulk soil (8.4° ± 1.9°) and the rhizosphere (65° ± 9.2°). Drying was simulated using a lattice Boltzmann single-component, multiphase model. In our experiments, micromodels with higher contact angle surfaces took 4 times longer to completely dry versus micromodels with lower contact angle surfaces. Microstructure influenced drying rate as a function of saturation and controlled the spatial distribution of moisture within micromodels. In conclusion, lattice Boltzmann simulations accurately predicted pore-scale moisture retention patterns within micromodels with different structures and contact angles.},
doi = {10.1002/2016WR019862},
journal = {Water Resources Research},
number = 7,
volume = 53,
place = {United States},
year = {2017},
month = {6}
}