Entry flow vortices in polymer melt extrusion: A review

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F70883521%3A28110%2F17%3A63516105" target="_blank" >RIV/70883521:28110/17:63516105 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1063/1.4982983" target="_blank" >http://dx.doi.org/10.1063/1.4982983</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1063/1.4982983" target="_blank" >10.1063/1.4982983</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Entry flow vortices in polymer melt extrusion: A review

Popis výsledku v původním jazyce

Although, circular or planar abrupt entry flows are geometrically very simple hydrodynamic problem highly viscoelastic polymer melts makes it very complex with extreme differences in velocities and stresses across the geometry. Despite these flows are very common in polymer melt extrusion industry their strongly non-viscometric and transient nature represents exceedingly challenging task for experimental as well as theoretical investigation and consequently complicates their fully understanding. Polymer melts flowing through abrupt entry contractions exhibit several unique features of which the vortices are one of them. Occurrence of infinitesimal stress singularity in the salient corner leads to presence of weak concave Newtonian viscous vortex. Moreover, polymer melts with increasing extensional to shear viscosity (Trouton) ratio as a function of flow rate exhibit strong convex elastic vortex caused by complete reorientation of stress field near the re-entrant corner (infinite stress singularity point) as a result of momentum balance in the flow direction. This leads to separation of the flow into the primary &quot;funnel-shaped&quot; flow around the centre line/plane on which the secondary recirculation flow(s) in the corner(s) (vortices) are superimposed. Polymer melt captured in the vortex very slowly rotates in the direction opposite to the main flow direction (2D simplification) or takes a helical path moving also in the third direction (real 3D flow). Since the first visual experimental observation performed by Tordella as well as preliminary theoretical prediction made by Langlois and Rivlin at the end of the 1950s this phenomenon represents one of the most fundamental rheological problem ever. In this review paper, the most important experimental as well as theoretical papers focused on entry flow vortices are reviewed and discussed.

Název v anglickém jazyce

Entry flow vortices in polymer melt extrusion: A review

Popis výsledku anglicky

Although, circular or planar abrupt entry flows are geometrically very simple hydrodynamic problem highly viscoelastic polymer melts makes it very complex with extreme differences in velocities and stresses across the geometry. Despite these flows are very common in polymer melt extrusion industry their strongly non-viscometric and transient nature represents exceedingly challenging task for experimental as well as theoretical investigation and consequently complicates their fully understanding. Polymer melts flowing through abrupt entry contractions exhibit several unique features of which the vortices are one of them. Occurrence of infinitesimal stress singularity in the salient corner leads to presence of weak concave Newtonian viscous vortex. Moreover, polymer melts with increasing extensional to shear viscosity (Trouton) ratio as a function of flow rate exhibit strong convex elastic vortex caused by complete reorientation of stress field near the re-entrant corner (infinite stress singularity point) as a result of momentum balance in the flow direction. This leads to separation of the flow into the primary &quot;funnel-shaped&quot; flow around the centre line/plane on which the secondary recirculation flow(s) in the corner(s) (vortices) are superimposed. Polymer melt captured in the vortex very slowly rotates in the direction opposite to the main flow direction (2D simplification) or takes a helical path moving also in the third direction (real 3D flow). Since the first visual experimental observation performed by Tordella as well as preliminary theoretical prediction made by Langlois and Rivlin at the end of the 1950s this phenomenon represents one of the most fundamental rheological problem ever. In this review paper, the most important experimental as well as theoretical papers focused on entry flow vortices are reviewed and discussed.

Druh

D - Stať ve sborníku

CEP obor

—

OECD FORD obor

10404 - Polymer science

Projekt

<a href="/cs/project/GA16-05886S" target="_blank" >GA16-05886S: Výzkum vlivu smykové a tahové reologie polymerních tavenin na stabilitu produkce meltblown nanovláken a fólií</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2017

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název statě ve sborníku

AIP Conference Proceedings

ISBN

978-0-7354-1513-3

ISSN

0094-243X

e-ISSN

neuvedeno

Počet stran výsledku

21

Strana od-do

—

Název nakladatele

American Institute of Physics Publising Inc.

Místo vydání

Melville

Místo konání akce

Zlín

Datum konání akce

26. 7. 2017

Typ akce podle státní příslušnosti

WRD - Celosvětová akce

Kód UT WoS článku

—