title: Elastic instabilities during the flow of hydrolyzed polyacrylamide solution in porous media: effect of pore-shape and salt.
abstract: We experimentally investigate the flow of hydrolyzed polyacrylamide (HPAM) solution with and without salt in model porous media at high Weissenberg numbers (Wi > 1.0). The effect of pore shapes on the flow pattern and pressure drop is explored by using periodic arrays of circular and square pillars in aligned and staggered layouts. In the apparent shear-thinning regime, we observe stationary dead zones upstream of the pillars. In addition, we confirm that the size of stationary dead zones correlates with the level of shear-thinning, by varying the amount of salt in HPAM solution. At higher shear rates (or Wi), these dead zones are periodically washed away. We present the mechanism of this elastic instability and characterize it based on the pressure drop fluctuation spectral density.
authors.affiliation: Department of Geosciences and Engineering, Delft University of Technology, Delft, The Netherlands. D.Kawale@tudelft.nl and Department of Chemical Engineering, Delft University of Technology, Delft, The Netherlands. P.E.Boukany@tudelft.nl and Dutch Polymer Institute (DPI), P.O.Box 902, 9600 AX, Eindhoven, The Netherlands.
authors.forename: Durgesh
authors.initials: D
authors.lastname: Kawale
authors.affiliation: Department of Chemical Engineering, Delft University of Technology, Delft, The Netherlands. P.E.Boukany@tudelft.nl.
authors.forename: Esteban
authors.initials: E
authors.lastname: Marques
authors.affiliation: Department of Geosciences and Engineering, Delft University of Technology, Delft, The Netherlands. D.Kawale@tudelft.nl.
authors.forename: Pacelli L J
authors.initials: PL
authors.lastname: Zitha
authors.affiliation: Department of Chemical Engineering, Delft University of Technology, Delft, The Netherlands. P.E.Boukany@tudelft.nl.
authors.forename: Michiel T
authors.initials: MT
authors.lastname: Kreutzer
authors.affiliation: Department of Geosciences and Engineering, Delft University of Technology, Delft, The Netherlands. D.Kawale@tudelft.nl.
authors.forename: William R
authors.initials: WR
authors.lastname: Rossen
authors.affiliation: Department of Chemical Engineering, Delft University of Technology, Delft, The Netherlands. P.E.Boukany@tudelft.nl.
authors.forename: Pouyan E
authors.identifier: http://orcid.org/0000-0002-2262-5795
authors.initials: PE
authors.lastname: Boukany