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Drawing of Newtonian hollow fibres: Effects of surface tension, cooling, internal pressurisation and inertia on steady states and stability

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dc.contributor.authorPapri, N.N.
dc.contributor.authorWylie, J.J.
dc.contributor.authorStokes, Y.M.
dc.date.issued2025
dc.description.abstractWe consider the drawing of a hollow Newtonian fibre with temperature-dependent viscosity. The drawing is affected by surface tension, inertia, hole pressurisation and externally applied cooling. We apply long-wavelength techniques to determine the steady states and examine their stability. In the presence of surface tension but with no cooling or internal hole pressure, we show the counter-intuitive result that the hole radius at the outlet of the device is a non-monotonic function of the hole radius at the inlet. We also show that if the internal hole is pressurised and the hole size at the inlet is sufficiently large, then the exit temperature of the fibre is a non-monotonic function of the applied cooling rate. We have found a number of surprising mechanisms related to how the various physical effects influence the stability of drawing. For the isothermal case, we show that increasing the internal hole pressure has a destabilising effect for non-zero surface tension while the stability is completely independent of the internal hole pressure for zero surface tension. We further show that there is a complicated interplay between internal hole pressure, external cooling and surface tension in determining the stability and that it is possible that increasing the hole size at the inlet can act to destabilise, then stabilise and finally destabilise the flow. We discuss the mechanisms that determine the counter-intuitive steady-state behaviour and stability.
dc.description.statementofresponsibilityNazmun N. Papri, Jonathan J. Wylie, Yvonne M. Stokes
dc.identifier.citationJournal of Fluid Mechanics, 2025; 1010:A67-1-A67-34
dc.identifier.doi10.1017/jfm.2025.381
dc.identifier.issn0022-1120
dc.identifier.issn1469-7645
dc.identifier.orcidStokes, Y.M. [0000-0003-0027-6077]
dc.identifier.urihttps://hdl.handle.net/2440/147336
dc.language.isoen
dc.publisherCambridge University Press
dc.relation.granthttp://purl.org/au-research/grants/arc/FT160100108
dc.rights©The Author(s), 2025. Published by Cambridge University Press. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (https://creativecommons.org/ licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.
dc.source.urihttps://doi.org/10.1017/jfm.2025.381
dc.subjectCapillary flows; hollow Newtonian fibre temperature-dependent viscosity; stability analysis; surface tension
dc.titleDrawing of Newtonian hollow fibres: Effects of surface tension, cooling, internal pressurisation and inertia on steady states and stability
dc.typeJournal article
pubs.publication-statusPublished

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