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Modelling Reverse Roll Coating flow with dynamic wetting lines and inelastic shear thinning fluids

S.O.S. Echendu, H.R. Tamaddon-Jahromi, Michael Webster Orcid Logo

Applied Rheology, Volume: 23, Issue: 6, Start page: 62388

Swansea University Author: Michael Webster Orcid Logo

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DOI (Published version): 10.3933/ApplRheol-23-62388

Abstract

This study addresses the numerical solution of high-speed reverse roller coating flow associated with the industrial process of thin-film paint-coatings of strip-steel. The modelling includes viscous inelastic rheology, meniscus and dynamic wetting lines, accomplished through a semi-implicit time-st...

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Published in: Applied Rheology
Published: 2013
URI: https://cronfa.swan.ac.uk/Record/cronfa24191
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first_indexed 2015-11-09T11:28:12Z
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fullrecord <?xml version="1.0"?><rfc1807><datestamp>2015-11-08T19:28:07.0319939</datestamp><bib-version>v2</bib-version><id>24191</id><entry>2015-11-08</entry><title>Modelling Reverse Roll Coating flow with dynamic wetting lines and inelastic shear thinning fluids</title><swanseaauthors><author><sid>b6a811513b34d56e66489512fc2c6c61</sid><ORCID>0000-0002-7722-821X</ORCID><firstname>Michael</firstname><surname>Webster</surname><name>Michael Webster</name><active>true</active><ethesisStudent>false</ethesisStudent></author></swanseaauthors><date>2015-11-08</date><deptcode>EEN</deptcode><abstract>This study addresses the numerical solution of high-speed reverse roller coating flow associated with the industrial process of thin-film paint-coatings of strip-steel. The modelling includes viscous inelastic rheology, meniscus and dynamic wetting lines, accomplished through a semi-implicit time-stepping finite element Taylor-Galerkin/pressure-correction scheme, coupled with a differential free-surface location technique. Flow structures are examined in detail around the meniscus, nip and wetting line regions, analysed via streamline and shear rates patterns, surface distributional lift and localised nip-pressures. For Newtonian coatings, two vortex transfer modes are visible: one large structure commencing just downstream of the meniscus; and a second miniscule structure in the nip-vicinity, upstream of the wetting line, which is accompanied by increase in localised pressure. This secondary nip-vortex tends to increase in size as power-law index is decreased, with reduction in localised pressure. Effects of parameter variation are analysed in nip-gap size, adjustment of applicator roller-substrate speed-ratio and levels of surface tension. Positive peak-pressures tend to increase with decrease in nip-gap size. At low nip-gap size, negative peak pressures are observed around the substrate-wetting line contact region. At higher speed-ratios, positive peak pressures are seen to increase with less recirculation apparent around the contact zone. Significantly and upon surface tension increase, the dynamic wetting line is sucked further inwards towards the nip-gap, stimulating a localised wetting line-foil third vortex structure. This minor third vortex in the contact zone increases with increased levels of surface tension, causing an apparent reduction in the thickness of film-leakage.</abstract><type>Journal Article</type><journal>Applied Rheology</journal><volume>23</volume><journalNumber>6</journalNumber><paginationStart>62388</paginationStart><publisher/><keywords>Reverse roll coating, dynamic wetting, surface tension, power-law model, Carreau model.</keywords><publishedDay>31</publishedDay><publishedMonth>12</publishedMonth><publishedYear>2013</publishedYear><publishedDate>2013-12-31</publishedDate><doi>10.3933/ApplRheol-23-62388</doi><url/><notes></notes><college>COLLEGE NANME</college><department>Engineering</department><CollegeCode>COLLEGE CODE</CollegeCode><DepartmentCode>EEN</DepartmentCode><institution>Swansea University</institution><apcterm/><lastEdited>2015-11-08T19:28:07.0319939</lastEdited><Created>2015-11-08T19:26:03.7756038</Created><path><level id="1">Faculty of Science and Engineering</level><level id="2">School of Engineering and Applied Sciences - Uncategorised</level></path><authors><author><firstname>S.O.S.</firstname><surname>Echendu</surname><order>1</order></author><author><firstname>H.R.</firstname><surname>Tamaddon-Jahromi</surname><order>2</order></author><author><firstname>Michael</firstname><surname>Webster</surname><orcid>0000-0002-7722-821X</orcid><order>3</order></author></authors><documents/><OutputDurs/></rfc1807>
spelling 2015-11-08T19:28:07.0319939 v2 24191 2015-11-08 Modelling Reverse Roll Coating flow with dynamic wetting lines and inelastic shear thinning fluids b6a811513b34d56e66489512fc2c6c61 0000-0002-7722-821X Michael Webster Michael Webster true false 2015-11-08 EEN This study addresses the numerical solution of high-speed reverse roller coating flow associated with the industrial process of thin-film paint-coatings of strip-steel. The modelling includes viscous inelastic rheology, meniscus and dynamic wetting lines, accomplished through a semi-implicit time-stepping finite element Taylor-Galerkin/pressure-correction scheme, coupled with a differential free-surface location technique. Flow structures are examined in detail around the meniscus, nip and wetting line regions, analysed via streamline and shear rates patterns, surface distributional lift and localised nip-pressures. For Newtonian coatings, two vortex transfer modes are visible: one large structure commencing just downstream of the meniscus; and a second miniscule structure in the nip-vicinity, upstream of the wetting line, which is accompanied by increase in localised pressure. This secondary nip-vortex tends to increase in size as power-law index is decreased, with reduction in localised pressure. Effects of parameter variation are analysed in nip-gap size, adjustment of applicator roller-substrate speed-ratio and levels of surface tension. Positive peak-pressures tend to increase with decrease in nip-gap size. At low nip-gap size, negative peak pressures are observed around the substrate-wetting line contact region. At higher speed-ratios, positive peak pressures are seen to increase with less recirculation apparent around the contact zone. Significantly and upon surface tension increase, the dynamic wetting line is sucked further inwards towards the nip-gap, stimulating a localised wetting line-foil third vortex structure. This minor third vortex in the contact zone increases with increased levels of surface tension, causing an apparent reduction in the thickness of film-leakage. Journal Article Applied Rheology 23 6 62388 Reverse roll coating, dynamic wetting, surface tension, power-law model, Carreau model. 31 12 2013 2013-12-31 10.3933/ApplRheol-23-62388 COLLEGE NANME Engineering COLLEGE CODE EEN Swansea University 2015-11-08T19:28:07.0319939 2015-11-08T19:26:03.7756038 Faculty of Science and Engineering School of Engineering and Applied Sciences - Uncategorised S.O.S. Echendu 1 H.R. Tamaddon-Jahromi 2 Michael Webster 0000-0002-7722-821X 3
title Modelling Reverse Roll Coating flow with dynamic wetting lines and inelastic shear thinning fluids
spellingShingle Modelling Reverse Roll Coating flow with dynamic wetting lines and inelastic shear thinning fluids
Michael Webster
title_short Modelling Reverse Roll Coating flow with dynamic wetting lines and inelastic shear thinning fluids
title_full Modelling Reverse Roll Coating flow with dynamic wetting lines and inelastic shear thinning fluids
title_fullStr Modelling Reverse Roll Coating flow with dynamic wetting lines and inelastic shear thinning fluids
title_full_unstemmed Modelling Reverse Roll Coating flow with dynamic wetting lines and inelastic shear thinning fluids
title_sort Modelling Reverse Roll Coating flow with dynamic wetting lines and inelastic shear thinning fluids
author_id_str_mv b6a811513b34d56e66489512fc2c6c61
author_id_fullname_str_mv b6a811513b34d56e66489512fc2c6c61_***_Michael Webster
author Michael Webster
author2 S.O.S. Echendu
H.R. Tamaddon-Jahromi
Michael Webster
format Journal article
container_title Applied Rheology
container_volume 23
container_issue 6
container_start_page 62388
publishDate 2013
institution Swansea University
doi_str_mv 10.3933/ApplRheol-23-62388
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Engineering and Applied Sciences - Uncategorised{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Engineering and Applied Sciences - Uncategorised
document_store_str 0
active_str 0
description This study addresses the numerical solution of high-speed reverse roller coating flow associated with the industrial process of thin-film paint-coatings of strip-steel. The modelling includes viscous inelastic rheology, meniscus and dynamic wetting lines, accomplished through a semi-implicit time-stepping finite element Taylor-Galerkin/pressure-correction scheme, coupled with a differential free-surface location technique. Flow structures are examined in detail around the meniscus, nip and wetting line regions, analysed via streamline and shear rates patterns, surface distributional lift and localised nip-pressures. For Newtonian coatings, two vortex transfer modes are visible: one large structure commencing just downstream of the meniscus; and a second miniscule structure in the nip-vicinity, upstream of the wetting line, which is accompanied by increase in localised pressure. This secondary nip-vortex tends to increase in size as power-law index is decreased, with reduction in localised pressure. Effects of parameter variation are analysed in nip-gap size, adjustment of applicator roller-substrate speed-ratio and levels of surface tension. Positive peak-pressures tend to increase with decrease in nip-gap size. At low nip-gap size, negative peak pressures are observed around the substrate-wetting line contact region. At higher speed-ratios, positive peak pressures are seen to increase with less recirculation apparent around the contact zone. Significantly and upon surface tension increase, the dynamic wetting line is sucked further inwards towards the nip-gap, stimulating a localised wetting line-foil third vortex structure. This minor third vortex in the contact zone increases with increased levels of surface tension, causing an apparent reduction in the thickness of film-leakage.
published_date 2013-12-31T03:28:39Z
_version_ 1763751094298607616
score 11.012723

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