On the hydrodynamic focusing for producing microemulsions via tip streaming

In this work we study experimentally and numerically the stability of hydrodynamic focusing to produce microemulsions. The jetting regime was produced experimentally for the lowest outer viscosity, while microdripping was obtained for the highest outer viscosity. The liquid ejection for small capill...

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Autores: López, M., Cabezas, M. G., Montanero, J. M., Herrada Gutiérrez, Miguel Ángel
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:2022
País:España
Institución:Universidad de Sevilla (US)
Repositorio:idUS. Depósito de Investigación de la Universidad de Sevilla
OAI Identifier:oai:idus.us.es:11441/134359
Acceso en línea:https://hdl.handle.net/11441/134359
https://doi.org/10.1017/jfm.2022.2
Access Level:acceso abierto
Palabra clave:Absolute/convective instability
Drops
Microfluidics
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spelling On the hydrodynamic focusing for producing microemulsions via tip streamingLópez, M.Cabezas, M. G.Montanero, J. M.Herrada Gutiérrez, Miguel ÁngelAbsolute/convective instabilityDropsMicrofluidicsIn this work we study experimentally and numerically the stability of hydrodynamic focusing to produce microemulsions. The jetting regime was produced experimentally for the lowest outer viscosity, while microdripping was obtained for the highest outer viscosity. The liquid ejection for small capillary numbers stabilizes as the distance between the feeding capillary and the focusing orifice decreases. The comparison between confined selective withdrawal and stretched flow focusing for the largest outer viscosity shows that confined selective withdrawal significantly enhances the stability of the microdripping mode, which entails a significant reduction of the minimum value of the droplet diameter. When surfactants are dissolved in the inner liquid at sufficiently large concentrations, we observe a significant decrease in both the minimum flow rate leading to tip streaming and the droplet diameter. The surfactant monolayer stabilizes the meniscus and promotes the transition from microdripping to jetting. The global stability analysis shows that jetting via tip streaming becomes unstable due to the growth of an oscillatory perturbation. The unstable perturbation affects the tapering meniscus for the lowest outer viscosity, which explains why the meniscus oscillates in the experiments. The critical flow rate ratio is accurately predicted by the global stability analysis in most of the experiments with the lowest outer viscosity. For the highest outer viscosity, the global stability analysis correctly predicts the microdripping mode and allows one to calculate the droplet emission frequency in that mode.Gobierno de Extremadura GR18175Ministerio de Ciencia y Educacion PID2019-108278RB-C32/ AEI/10.13039/501100011033Junta de Andalucía P18-FR-3623Cambridge University PressIngeniería Aeroespacial y Mecánica de FluidosTEP219: Física de fluidos y microfluídica2022info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionapplication/pdfapplication/pdfhttps://hdl.handle.net/11441/134359https://doi.org/10.1017/jfm.2022.2reponame:idUS. Depósito de Investigación de la Universidad de Sevillainstname:Universidad de Sevilla (US)InglésJournal of Fluid Mechanics, 934, A47.GR18175PID2019-108278RB-C32/ AEI/10.13039/501100011033P18-FR-3623https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/on-the-hydrodynamic-focusing-for-producing-microemulsions-via-tip-streaming/60100F12AD34197A65FCF6AFA5ACAF72info:eu-repo/semantics/openAccessoai:idus.us.es:11441/1343592026-06-17T12:51:07Z
dc.title.none.fl_str_mv On the hydrodynamic focusing for producing microemulsions via tip streaming
title On the hydrodynamic focusing for producing microemulsions via tip streaming
spellingShingle On the hydrodynamic focusing for producing microemulsions via tip streaming
López, M.
Absolute/convective instability
Drops
Microfluidics
title_short On the hydrodynamic focusing for producing microemulsions via tip streaming
title_full On the hydrodynamic focusing for producing microemulsions via tip streaming
title_fullStr On the hydrodynamic focusing for producing microemulsions via tip streaming
title_full_unstemmed On the hydrodynamic focusing for producing microemulsions via tip streaming
title_sort On the hydrodynamic focusing for producing microemulsions via tip streaming
dc.creator.none.fl_str_mv López, M.
Cabezas, M. G.
Montanero, J. M.
Herrada Gutiérrez, Miguel Ángel
author López, M.
author_facet López, M.
Cabezas, M. G.
Montanero, J. M.
Herrada Gutiérrez, Miguel Ángel
author_role author
author2 Cabezas, M. G.
Montanero, J. M.
Herrada Gutiérrez, Miguel Ángel
author2_role author
author
author
dc.contributor.none.fl_str_mv Ingeniería Aeroespacial y Mecánica de Fluidos
TEP219: Física de fluidos y microfluídica
dc.subject.none.fl_str_mv Absolute/convective instability
Drops
Microfluidics
topic Absolute/convective instability
Drops
Microfluidics
description In this work we study experimentally and numerically the stability of hydrodynamic focusing to produce microemulsions. The jetting regime was produced experimentally for the lowest outer viscosity, while microdripping was obtained for the highest outer viscosity. The liquid ejection for small capillary numbers stabilizes as the distance between the feeding capillary and the focusing orifice decreases. The comparison between confined selective withdrawal and stretched flow focusing for the largest outer viscosity shows that confined selective withdrawal significantly enhances the stability of the microdripping mode, which entails a significant reduction of the minimum value of the droplet diameter. When surfactants are dissolved in the inner liquid at sufficiently large concentrations, we observe a significant decrease in both the minimum flow rate leading to tip streaming and the droplet diameter. The surfactant monolayer stabilizes the meniscus and promotes the transition from microdripping to jetting. The global stability analysis shows that jetting via tip streaming becomes unstable due to the growth of an oscillatory perturbation. The unstable perturbation affects the tapering meniscus for the lowest outer viscosity, which explains why the meniscus oscillates in the experiments. The critical flow rate ratio is accurately predicted by the global stability analysis in most of the experiments with the lowest outer viscosity. For the highest outer viscosity, the global stability analysis correctly predicts the microdripping mode and allows one to calculate the droplet emission frequency in that mode.
publishDate 2022
dc.date.none.fl_str_mv 2022
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv https://hdl.handle.net/11441/134359
https://doi.org/10.1017/jfm.2022.2
url https://hdl.handle.net/11441/134359
https://doi.org/10.1017/jfm.2022.2
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv Journal of Fluid Mechanics, 934, A47.
GR18175
PID2019-108278RB-C32/ AEI/10.13039/501100011033
P18-FR-3623
https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/on-the-hydrodynamic-focusing-for-producing-microemulsions-via-tip-streaming/60100F12AD34197A65FCF6AFA5ACAF72
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
application/pdf
dc.publisher.none.fl_str_mv Cambridge University Press
publisher.none.fl_str_mv Cambridge University Press
dc.source.none.fl_str_mv reponame:idUS. Depósito de Investigación de la Universidad de Sevilla
instname:Universidad de Sevilla (US)
instname_str Universidad de Sevilla (US)
reponame_str idUS. Depósito de Investigación de la Universidad de Sevilla
collection idUS. Depósito de Investigación de la Universidad de Sevilla
repository.name.fl_str_mv
repository.mail.fl_str_mv
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