**Slip length of branched hydrocarbon oils confined between iron surfaces**

S Mehrnia and PF Pelz, JOURNAL OF MOLECULAR LIQUIDS, 336, 116589 (2021).

DOI: 10.1016/j.molliq.2021.116589

In this paper, the slip length of branched hydrocarbon molecules, i.e., polyalphaolefin oils, under shear in a gap between iron surfaces were investigated utilizing large-scale Molecular Dynamics (MD) simulation. The results showed the expected singularity for the slip length with variation gap height. For large gap height, h -> infinity, the slip length approaches a constant asymptote lambda -> lambda(infinity). This study indicated that as the number of branches of the liquid molecule raise, the slip length lambda -> lambda(infinity) as well as viscosity increases. For given apparent shear rate, the friction force increased with increasing temperature due to the reduction of wall slip. MD Simulations demonstrate that the slip length of the polyalphaolefin-iron system increase by decreasing the liquid temperature, indicating an Arrhenius process. (C) 2021 Elsevier B.V. All rights reserved.

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