Shear behavior of squalane and tetracosane under extreme confinement. II. Confined film structure

Journal Article · Mon Dec 01 04:00:00 EST 1997 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.474172· OSTI ID:550464

Gupta, S A; Cochran, H D; Cummings, P T ^[1]

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1. Department of Chemical Engineering, University of Tennessee, Knoxville, Tennessee 37996-2200 (United States)

This paper focuses on the structural characteristics of confined squalane and tetracosane under shear flow conditions. Nonequilibrium molecular dynamics simulation is used to explore the rheology of these model lubricants. A preceding paper describes the molecular model and the simulation method, and examines interfacial slip. The lubricants are confined between model walls that have short chains tethered to them, thus screening the wall details. In this paper we examine the density profiles and chain conformations of the alkanes under shear flow conditions. Our results indicate a profound influence of the walls on the fluid structure. In particular, when the wall spacing is close to an integral multiple of the molecular diameter, tetracosane shows the formation of distinct layers with the molecules being in a fully extended state. This behavior is not observed for squalane. Under shear flow conditions the molecules tend to orient parallel to the walls, as would be expected, with a greater degree of orientation (a) close to the walls, (b) at the positions of local density maxima, and (c) at higher strain rates. {copyright} {ital 1997 American Institute of Physics.}

• Research Organization: Oak Ridge National Laboratory
• DOE Contract Number: AC05-96OR22464
• OSTI ID: 550464
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 23 Vol. 107; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
ALKANES
LIQUIDS
LUBRICANTS
MOLECULAR DYNAMICS METHOD
RHEOLOGY
SHEAR PROPERTIES
SIMULATION
SLIP FLOW
SQUALANE
THIN FILMS