Numerical study of interface tracking for the unsteady flow of two immiscible micropolar and Newtonian fluids through a horizontal channel with an unstable interface

Chandrawat, RK, Joshi, V and Beg, OA ORCID: https://orcid.org/0000-0001-5925-6711 2021, 'Numerical study of interface tracking for the unsteady flow of two immiscible micropolar and Newtonian fluids through a horizontal channel with an unstable interface' , Journal of Nanofluids . (In Press)

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Abstract

The dynamics of the interaction between immiscible fluids is relevant to numerous complex flows in nature and industry, including lubrication and coating processes, oil extraction, physicochemical separation techniques etc. In this article, the unsteady flow of two immiscible fluids i.e. an Eringen micropolar and Newtonian liquid, is considered in a horizontal channel. Despite the no-slip and hyper-stick boundary conditions at the channel wall, it is accepted that the fluid-fluid interface is unstable, and it travels from one position to another, and may even be deformed; hence the single momentum equation in the volume of fluid (VOF) method is combined with the continuum surface approach model to track the interface. The immiscible fluids are considered to flow under three applied pressure gradients (constant, decaying and periodic) and flow is analyzed under seamless shear stress over the entire interface. The modified cubic b-spline differential quadrature method (MCB-DQM) is used to solve the modeled coupled partial differential equations for the fluid interface evolution. The advection and tracking of the interface with time, wave number, and amplitude are illustrated through graphs. It is observed that the presence of micropolar parameters affects the interface with time. The novelty of the current study is that previous studies (which considered smooth and unstable movement of the micropolar fluid, the steady stream of two immiscible fluids and interface monitoring through different modes) are extended and generalized to consider unsteady flow of two immiscible Eringen micropolar and Newtonian fluids with a moving interface in a horizontal channel. For the decaying pressure gradient case, which requires more time to achieve the steady state, the peak of the waves resemble those for the constant pressure gradient case. The interface becomes steady for a more extensive time when a constant pressure gradient is applied. The interface becomes stable quickly with time as the micropolar parameter is decreased for the constant pressure gradient case i.e. weaker micropolar fluids encourage faster stabilization of the interface. With periodic pressure gradient, the interface takes more time to stabilize, and the crest of the waves is significantly higher in amplitude compared to the constant and decaying pressure cases. The simulations demonstrate the excellent ability of MCB-DQM to analyze complex interfacial immiscible flows.

Item Type: Article
Schools: Schools > School of Computing, Science and Engineering
Journal or Publication Title: Journal of Nanofluids
Publisher: American Scientific Publishers
ISSN: 2169-432X
Depositing User: OA Beg
Date Deposited: 04 Aug 2021 07:42
Last Modified: 28 Aug 2021 10:30
URI: http://usir.salford.ac.uk/id/eprint/61420

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