Capillary condensation and depinning transitions in open slits.

0547277 - ÚCHP 2022 RIV US eng J - Článek v odborném periodiku
Malijevský, Alexandr - Parry, A.O.
Capillary condensation and depinning transitions in open slits.
Physical Review E. Roč. 104, č. 4 (2021), č. článku 044801. ISSN 2470-0045. E-ISSN 2470-0053
Grant CEP: GA ČR(CZ) GA20-14547S
Institucionální podpora: RVO:67985858
Klíčová slova: critical-point shifts * universality * criicality
Obor OECD: Atomic, molecular and chemical physics (physics of atoms and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect)
Impakt faktor: 2.707, rok: 2021
Způsob publikování: Omezený přístup

We study the low-temperature phase equilibria of a fluid confined in an open capillary slit formed by twoparallel walls separated by a distance L which are in contact with a reservoir of gas. The top wall of the capillary is of finite length H while the bottom wall is considered of macroscopic extent. 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 and divides into three
regimes: 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. 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 which is determined explicitly. For long and intermediate capillaries, we show that there is an additional continuous phase transition in the condensed liquid-like phase, associated with the depinning of each meniscus as they round the upper open edges of the slit. Meniscus depinning is third-order for complete wetting and second-order for partial wetting. Detailed scaling theories are developed for these transitions and phase boundaries which connect with the theories of wedge (corner) filling and wetting encompassing interfacial fluctuation effects and the direct
influence of intermolecular forces.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 for different aspect ratios and contact angles.
Trvalý link: http://hdl.handle.net/11104/0323552