Journal article 438 views
Modelling Reverse Roll Coating flow with dynamic wetting lines and inelastic shear thinning fluids
S.O.S. Echendu,
H.R. Tamaddon-Jahromi,
Michael Webster 
Applied Rheology, Volume: 23, Issue: 6, Start page: 62388
Swansea University Author:
Michael Webster
Full text not available from this repository: check for access using links below.
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...
| Published in: | Applied Rheology |
|---|---|
| Published: |
2013
|
| URI: | https://cronfa.swan.ac.uk/Record/cronfa24191 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| 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. |
|---|---|
| Keywords: |
Reverse roll coating, dynamic wetting, surface tension, power-law model, Carreau model. |
| College: |
Faculty of Science and Engineering |
| Issue: |
6 |
| Start Page: |
62388 |