SKM 2023 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 35: Poster Session II
CPP 35.7: Poster
Mittwoch, 29. März 2023, 11:00–13:00, P1
Purely elastic instability of semi-dilute polymer solutions in shear flow — Pegah Shakeri1,2, •Michael Jung1,2, and Ralf Seemann1,2 — 1Universität des Saarlandes, Saarbrücken, Germany — 2Max Planck-Institute for Dynamics and Self-Organization, Göttingen, Germany
Polymer solutions in the semi-dilute regime are of considerable industrial importance. The complex rheological properties of such highly viscoelastic fluids and the complexity of their flow characteristics, especially in curved geometries, require a thorough experimental characterization of the dynamics of such fluid flows. We experimentally investigate the flow of highly elastic polymer solutions above their overlap concentrations in a microfluidic serpentine channel using pressure measurements and particle image velocimetry. Our results show that the flow resistance increases significantly at high Weissenberg numbers but vanishing Reynolds numbers, indicating the occurrence of a purely elastic instability. We show that the onset of instability can be scaled by including shear-dependent rheological properties of the polymer solutions in the nonlinear stability analysis. As a result, a universal criterion as a function of normalized polymer concentration is provided for scaling the onset of pure elastic instability in the semi-dilute regime independent of the type and molecular weight of the polymer.