Inhalt des Dokuments
Es gibt keine deutsche Übersetzung dieser Webseite.
Elastic flow instabilities in microfluidic serpentine channels
We discuss the onset of a purely elastic flow instability in serpentine channels, using a combined experimental, numerical and theoretical investigation. Good qualitative agreement is obtained between experiments, using dilute solutions of flexible polymers in microfluidic devices, and three-dimensional numerical simulations using the upper-convected Maxwell model  The results are confirmed by a simple theoretical analysis, based on the dimensionless criterion proposed by Pakdel & McKinley (PRL, 1996). We then determine the influence of fluid shear thinning on the onset of such purely-elastic flow instabilities and 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.
The good understanding of the onset of elastic instabilities can also be used to determine relaxation times of unknown solutions and we describe a microfluidic rheometer using a serpentine flow channel . In addition, we investigate the structure and magnitude of secondary flows, present in flows of visco-elastic fluids in curved geometries [3,5].
 Zilz et al, Geometric scaling of purely-elastic flow instabilities, JFM 712 (2012) 203-218
 Zilz et al, Serpentine channels: micro – rheometers for fluid relaxation times, Lab Chip (2014)
 Poole et al, Viscoelastic secondary flows in serpentine channels, JNNFM 201 (2013) 10–16
 Casanellas et al. Stabilizing effect of shear thinning on the onset of purely elastic instabilities
in serpentine microflows, Soft Matter, 2016, DOI: 10.1039/C6SM00326E
 Ducloué et al. Secondary flows of viscoelastic fluids in serpentine microchannels, Microfluid
Nanofluid (2019) 23: 33