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Pore‐scale water dynamics during drying and the impacts of structure and surface wettability
Author(s) -
Cruz Brian C.,
Furrer Jessica M.,
Guo YiSyuan,
Dougherty Daniel,
Hinestroza Hector F.,
Hernandez Jhoan S.,
Gage Daniel J.,
Cho Yong Ku,
Shor Leslie M.
Publication year - 2017
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1002/2016wr019862
Subject(s) - contact angle , wetting , moisture , materials science , soil water , loam , lattice boltzmann methods , capillary action , saturation (graph theory) , water content , soil science , composite material , geotechnical engineering , environmental science , mechanics , geology , physics , mathematics , combinatorics
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. Lattice Boltzmann simulations accurately predicted pore‐scale moisture retention patterns within micromodels with different structures and contact angles.