Unsteady squeezing flow of a magnetized nano-lubricant between parallel disks with Robin boundary conditions

Umavathi, JC; Patil, SL; Mahanthesh, B; Beg, OA

Abstract

The aim of the present work is to examine the impact of magnetized nanoparticles (NPs) in
enhancement of heat transport in a tribological system subjected to convective type heating (Robin) boundary
conditions. The regime examined comprises the squeezing transition of a magnetic (smart) Newtonian nanolubricant between two analogous disks under an axial magnetism. The lower disk is permeable whereas the upper
disk is solid. The mechanisms of haphazard motion of NPs and thermophoresis are simulated. The non-dimensional
problem is solved numerically using a finite difference method in the MATLAB bvp4c solver based on Lobotto
quadrature, to scrutinize the significance of thermophoresis parameter, squeezing number, Hartmann number,
Prandtl number and Brownian motion parameter on velocity, temperature, nanoparticle concentration, Nusselt
number, factor of friction and Sherwood number distributions. The obtained results for the friction factor are
validated against previously published results. It is found that friction factor at the disk increases with intensity in
applied magnetic field. The haphazard (Brownian) motion of nanoparticles causes an enhancement in thermal field.
Suction and injection are found to induce different effects on transport characteristics depending on the specification
of equal or unequal Biot numbers at the disks. The main quantitative outcome is that, unequal Biot numbers produce
significant cooling of the regime for both cases of disk suction or injection, indicating that Robin boundary
conditions yield substantial deviation from conventional thermal boundary conditions. Higher thermophoretic
parameter also elevates temperatures in the regime. The nanoparticles concentration at the disk is boosted with
higher values of Brownian motion parameter. The response of temperature is similar in both suction and injection
cases; however, this tendency is quite opposite for nanoparticle concentrations. In the core zone, the resistive
magnetic body force dominates and this manifests in a significant reduction in velocity i.e. damping. The heat buildup in squeeze films (which can lead to corrosion and degradation of surfaces) can be successfully removed with
magnetic nanoparticles leading to prolonged serviceability of lubrication systems and the need for less maintenance.

Citation

Umavathi, J., Patil, S., Mahanthesh, B., & Beg, O. (2021). Unsteady squeezing flow of a magnetized nano-lubricant between parallel disks with Robin boundary conditions. Proceedings of the Institution of Mechanical Engineers, Part N: Journal of Nanomaterials, Nanoengineering and Nanosystems, 235(3-4), 67-81. https://doi.org/10.1177/23977914211036562

• Journal Article Type: Article
• Acceptance Date: Jul 9, 2021
• Online Publication Date: Jul 28, 2021
• Publication Date: Sep 1, 2021
• Deposit Date: Jul 12, 2021
• Publicly Available Date: Jul 12, 2021
• Journal: Proceedings of the Institution of Mechanical Engineers, Part N: Journal of Nanomaterials, Nanoengineering and Nanosystems
• Print ISSN: 2397-7914
• Electronic ISSN: 2397-7922
• Publisher: SAGE Publications
• Volume: 235
• Issue: 3-4
• Pages: 67-81
• DOI: https://doi.org/10.1177/23977914211036562
• Publisher URL: https://doi.org/10.1177/23977914211036562
• Related Public URLs: https://journals.sagepub.com/home/pin
• Additional Information: Access Information : This is an Accepted Manuscript of an article which has been accepted for publication by Proceedings of the Institution of Mechanical Engineers, Part N: Journal of Nanomaterials, Nanoengineering and Nanosystems. Users who receive access to an article through a repository are reminded that the article is protected by copyright and reuse is restricted to non-commercial and no derivative uses. Users may also download and save a local copy of an article accessed in an institutional repository for the user's personal reference.