http://repositorio.unb.br/handle/10482/50465
Title: | Magnetic field effects on the surfactant concentration over ferrofluid droplet surfaces in shear flows |
Authors: | Pimenta, Paulo Henrique Neves Rebouças, Rodrigo B. Oliveira, Taygoara Felamingo de |
metadata.dc.identifier.orcid: | https://orcid.org/0000-0002-4145-5461 https://orcid.org/0000-0001-8982-3553 https://orcid.org/0000-0003-2957-537X |
metadata.dc.contributor.affiliation: | Federal Institute of Goiás, Department of Academic Areas IV University of Illinois Chicago, Department of Chemical Engineering University of Brasília, Department of Mechanical Engineering, Laboratory of Energy and Environment |
Assunto:: | Campo magnético Surfactantes Cisalhamento |
Issue Date: | 15-May-2024 |
Publisher: | Elsevier Inc. |
Citation: | PIMENTA, P. H. N.; REBOUÇAS, R. B.; OLIVEIRA, T. F. Magnetic field effects on the surfactant concentration over ferrofluid droplet surfaces in shear flows. Journal of Colloid and Interface Science, [S. l.], v. 662, 15 maio 2024, p. 438-445. DOI: https://doi.org/10.1016/j.jcis.2024.02.036. |
Abstract: | We investigate the impact of a magnetic field on surfactant concentration and interfacial forces across droplet surfaces within shear flows. Our analysis centers on a single two-dimensional ferrofluid droplet covered with surfactants, suspended in an immiscible, non-magnetizable liquid. The model combines incompressible Navier–Stokes equations and Maxwell's equations in the superparamagnetic limit in the single-fluid formulation, augmented by terms accounting for Marangoni, capillary, and magnetic forces at the droplet interface. We solve the surfactant convection-diffusion equation at the surface, while a non-linear Langmuir equation of state relates surfactant concentration to surface tension. The model is numerically solved using finite differences, a level-set method for multiphase flow computation, and the closest-point method for concentration equation. Our findings reveal that even though the surfactant is magnetically neutral, the presence of a magnetic field significantly modifies its distribution at the interface. A magnetic field perpendicular to the primary flow direction shifts the maximum concentration zone from the droplet tips toward the flow vorticity direction, while a parallel field produces the opposite effect. Alterations in surfactant distribution directly impact the surface tension field, offering a potential wireless means of controlling droplet dynamics. |
metadata.dc.description.unidade: | Faculdade de Tecnologia (FT) Departamento de Engenharia Mecânica (FT ENM) |
DOI: | https://doi.org/10.1016/j.jcis.2024.02.036 |
metadata.dc.relation.publisherversion: | https://www.sciencedirect.com/science/article/abs/pii/S0021979724002728?via%3Dihub |
Appears in Collections: | Artigos publicados em periódicos e afins |
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