Evaluation of methods using topology and integral geometry to assess wettability.
File(s)
Published version
OA Location
Author(s)
Blunt, MJ
Akai, T
Bijeljic, B
Type
Journal Article
Abstract
HYPOTHESIS: The development of high-resolution in situ imaging has allowed contact angles to be measured directly inside porous materials. We evaluate the use of concepts in integral geometry to determine contact angle. Specifically, we test the hypothesis that it is possible to determine an average contact angle from measurements of the Gaussian curvature of the fluid/fluid meniscus using the Gauss-Bonnet theorem. THEORY AND SIMULATION: We show that it is not possible to unambiguously determine an average contact angle from the Gauss-Bonnet theorem. We instead present an approximate relationship: 2πn(1-cosθ)=4π-∫κG12dS12, where n is the number of closed loops of the three-phase contact line where phases 1 and 2 contact the surface, θ is the average contact angle, while κG12 is the Gaussian curvature of the fluid meniscus which is integrated over its surface S12. We then use the results of pore-scale lattice Boltzmann simulations to assess the accuracy of this approach to determine a representative contact angle for two-phase flow in porous media. FINDINGS: We show that in simple cases with a flat solid surface, the approximate expression works well. When applied to simulations on pore space images, the equation provides a robust estimate of contact angle, accurate to within 3°, when averaged over many fluid clusters, although individual values can have significant errors because of the approximations used in the calculation.
Date Issued
2020-05-05
Date Acceptance
2020-04-27
Start Page
99
End Page
108
Journal / Book Title
J Colloid Interface Sci
Volume
576
Copyright Statement
Copyright The Author(s). Published by Elsevier Inc.This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
Sponsor
Total E&P UK Limited
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/32413784
S0021-9797(20)30580-4
Grant Number
4200072704
Subjects
Contact angle
Gauss-Bonnet theorem
Gaussian curvature
Imaging
Interfacial area
Multiphase flow
Pore-scale
Porous media
Two-phase flow
Wettability
Chemical Physics
02 Physical Sciences
03 Chemical Sciences
09 Engineering
Publication Status
Published online
Coverage Spatial
United States