Influence of addition of carbon nanotubes on rheological properties of selected liquid lubricants - a computer simulation study

Anjali Chopra; Szymon Winczewski

doi:10.17466/tq2020/24.4/c

Influence of addition of carbon nanotubes on rheological properties of selected liquid lubricants - a computer simulation study

Abstract

This work is motivated by the improvement of anti-friction properties of lubricants by addition of CNTs proved experimentally in literature. In particular, a methodology is developed to compute the shear viscosity of liquid lubricants (Propylene Glycol) based on Molecular Dynamics simulation. Non-Equilibrium molecular dynamics (NEMD) approach is used with a reactive force field ReaxFF implemented in LAMMPS. The simulations are performed using the canonical (NVT) ensemble with the so-called SLLOD algorithm. Couette flow is imposed on the system by using Lees-Edwards periodic boundary conditions. Suitable parameters such as simulation time and imposed shear velocity are obtained. Using these parameters, the influence of addition of 27 wt% CNTs to Propylene Glycol on its viscosity is analyzed. Results show that 3.2 million time-steps with a 0.1 fs time-step size is not sufficient for the system to reach equilibrium state for such calculations. With the available computational resources, a shear velocity of 5 × 10−5Å/fs was observed to give viscosity value with approximately 43% error as compared to the experimental value. Moreover, the lubricant exhibited a shear thinning behaviour with increasing shear rates. CNTs enhanced the lubricant’s viscosity by 100-190% depending upon the averaging method used for calculation.

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DOI:: Digital Object Identifier (open in new tab) 10.17466/tq2020/24.4/c
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Category:: Articles
Type:: artykuły w czasopismach
Published in:: TASK Quarterly no. 24, pages 345 - 388,
ISSN: 1428-6394
Language:: English
Publication year:: 2020
Bibliographic description:: Chopra A., Winczewski S.: Influence of addition of carbon nanotubes on rheological properties of selected liquid lubricants - a computer simulation study// TASK Quarterly -Vol. 24,iss. 4 (2020), s.345-388
DOI:: Digital Object Identifier (open in new tab) 10.17466/tq2020/24.4/c
Verified by:: Gdańsk University of Technology