The stabilizing effect of shear thinning on the onset of purely elastic instabilities in serpentine microflows.
We determine both experimentally and numerically the onset of elastic flow instabilities in viscoelastic polymer solutions with different levels of shear thinning. Previous experiments realized in microfluidic serpentine channels using dilute polymeric solutions showed that the onset of elastic instabilities strongly depends on the channel curvature. The scaling dependence is well captured by the general instability scaling criterion proposed by Pakdel and McKinley [Phys. Rev. Lett., 1996, 76, 2459:1-4]. We determine here the influence of fluid shear thinning on the onset of such purely-elastic flow instabilities. By testing a set of polyethylene oxide solutions of high molecular weight at different polymer concentrations in microfluidic serpentine channels we observe that shear thinning has a stabilizing effect on the microfluidic flow. Three-dimensional numerical simulations performed using the White-Metzner model predict similar trends, which are not captured by a simple scaling analysis using the Pakdel-McKinley criterion.
PMMH, UMR 7636 CNRS - ESPCI Paris - Université Pierre et Marie Curie Université Paris Diderot, 10 rue Vauquelin, F-75231 Paris CEDEX 05, France. anke.lindner@espci.fr and Laboratoire Matière et Systèmes Complexes, CNRS UMR 7057-Université Paris Diderot, 10 rue Alice Domond et Léonie Duquet, 75205 Paris CEDEX 05, France.
Laura
L
Casanellas
Departamento de Engenharia Química, CEFT, Faculdade de Engenharia da Universidade do Porto, Rua Dr Roberto Frias, 4200-465 Porto, Portugal.
Manuel A
MA
Alves
School of Engineering, University of Liverpool, Brownlow Hill, Liverpool L69 3GH, UK.
Robert J
RJ
Poole
Laboratoire Matière et Systèmes Complexes, CNRS UMR 7057-Université Paris Diderot, 10 rue Alice Domond et Léonie Duquet, 75205 Paris CEDEX 05, France.
Sandra
S
Lerouge
PMMH, UMR 7636 CNRS - ESPCI Paris - Université Pierre et Marie Curie Université Paris Diderot, 10 rue Vauquelin, F-75231 Paris CEDEX 05, France. anke.lindner@espci.fr.
Anke
A
Lindner