Title: Thin Films in Partial Wetting: Internal Selection of Contact-Line Dynamics

Abstract

When 5 a liquid touches a solid surface, it spreads to minimize the system’s energy. The classic thin-film model describes the spreading as an interplay between gravity, capillarity and viscous forces, but cannot see an end to this process as it does not account for the nonhydrodynamic liquid–solid interactions. Even though these interactions are important only close to the contact line, where the liquid, solid and gas meet, they have macroscopic implications: in the partial-wetting regime, a liquid puddle ultimately stops spreading. We show that 10 by incorporating these intermolecular interactions, the free energy of the system at equilibrium can be cast in a Cahn–Hilliard framework with a height-dependent interfacial tension. Utilizing this free energy, we derive a mesoscopic thin-film model that describes statics and dynamics of liquid spreading in the partial-wetting regime. The height-dependence of the interfacial tension introduces a localized apparent slip in the contact-line region and leads to compactly-supported spreading states. In our model, the contact line dynamics emerge naturally as 15 part of the solution and are therefore nonlocally coupled to the bulk flow. Surprisingly, we find that even in the gravity-dominated regime, the dynamic contact angle follows the Cox–Voinov law.

Authors:

Alizadeh Pahlavan, Amir ^[1]; Cueto-Felgueroso, Luis ^[2]; McKinley, Gareth H. ^[1]; Juanes, Ruben ^[1]

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+ Show Author Affiliations

1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
2. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Technical Univ. of Madrid, Madrid (Spain)

Publication Date:

2015-07-17

Research Org.:

Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Univ. of Texas, Austin, TX (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR) (SC-21)

OSTI Identifier:

1505719

Alternate Identifier(s):

OSTI ID: 1195696

Grant/Contract Number:  

SC0003907

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review Letters

Additional Journal Information:

Journal Volume: 115; Journal Issue: 3; Journal ID: ISSN 0031-9007

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS