The edge contact angle, capillary condensation and meniscus depinning
File(s)
Accepted version
Author(s)
Parry, Andrew
Malijevsky, Alexandr
Type
Journal Article
Abstract
We study the phase equilibria of a fluid confined in an open capillary slit formed when a wall
of finite length H is brought a distance L away from a second macroscopic surface. This system
shows rich phase equilibria arising from the competition between two different types of capillary
condensation, corner filling and meniscus depinning transitions depending on the value of the aspect
ratio a = L/H. For long capillaries, with a < 2/π, the condensation is of type I involving menisci
which are pinned at the top edges at the ends of the capillary characterized by an edge contact
angle. For intermediate capillaries, with 2/π < a < 1, depending on the value of the contact angle
the condensation may be of type I or of type II, in which the menisci overspill into the reservoir
and there is no pinning. For short capillaries, with a > 1, condensation is always of type II. In all
regimes, capillary condensation is completely suppressed for sufficiently large contact angles. We
show that there is an additional continuous, third-order phase transition in the condensed liquidlike phase, associated with the depinning of each meniscus as they round the upper open edges of
the slit. Finite-size scaling predictions are developed for these transitions and phase boundaries
which connect with the fluctuation theories of wetting and filling transitions. We test several of our
predictions using a fully microscopic Density Functional Theory which allows us to study the two
types of capillary condensation and its suppression at the molecular level.
of finite length H is brought a distance L away from a second macroscopic surface. This system
shows rich phase equilibria arising from the competition between two different types of capillary
condensation, corner filling and meniscus depinning transitions depending on the value of the aspect
ratio a = L/H. For long capillaries, with a < 2/π, the condensation is of type I involving menisci
which are pinned at the top edges at the ends of the capillary characterized by an edge contact
angle. For intermediate capillaries, with 2/π < a < 1, depending on the value of the contact angle
the condensation may be of type I or of type II, in which the menisci overspill into the reservoir
and there is no pinning. For short capillaries, with a > 1, condensation is always of type II. In all
regimes, capillary condensation is completely suppressed for sufficiently large contact angles. We
show that there is an additional continuous, third-order phase transition in the condensed liquidlike phase, associated with the depinning of each meniscus as they round the upper open edges of
the slit. Finite-size scaling predictions are developed for these transitions and phase boundaries
which connect with the fluctuation theories of wetting and filling transitions. We test several of our
predictions using a fully microscopic Density Functional Theory which allows us to study the two
types of capillary condensation and its suppression at the molecular level.
Date Issued
2021-09-08
Date Acceptance
2021-08-12
Citation
Physical Review Letters, 2021, 127, pp.1-5
ISSN
0031-9007
Publisher
American Physical Society
Start Page
1
End Page
5
Journal / Book Title
Physical Review Letters
Volume
127
Copyright Statement
© 2021 American Physical Society
Identifier
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.127.115703
Subjects
Science & Technology
Physical Sciences
Physics, Multidisciplinary
Physics
TRANSITION
General Physics
01 Mathematical Sciences
02 Physical Sciences
09 Engineering
Publication Status
Published
Date Publish Online
2021-09-08