Paper Number
PO45
Session
Poster Session
Title
Volumetric evolution of elastic turbulence in porous media
Presentation Date and Time
October 12, 2022 (Wednesday) 6:30
Track / Room
Poster Session / Riverwalk A
Authors
- Carlson, Daniel W. (Okinawa Institute of Science and Technology)
- Toda-Peters, Kazumi (Okinawa Institute of Science and Technology)
- Shen, Amy Q. (Okinawa Institute of Science and Technology)
- Haward, Simon J. (Okinawa Institute of Science and Technology)
Author and Affiliation Lines
Daniel W. Carlson, Kazumi Toda-Peters, Amy Q. Shen and Simon J. Haward
Okinawa Institute of Science and Technology, Okinawa, Japan
Speaker / Presenter
Carlson, Daniel W.
Keywords
experimental methods; flow-induced instabilities; polymer solutions
Text of Abstract
Viscoelastic flow instability, which is compelled by elastic effects rather than inertia, can be driven to a chaotic state termed elastic turbulence (ET) manifested as strong velocity fluctuations with an algebraic decay in the frequency spectrum and increased mixing. We report the first spatiotemporally complete description of ET by considering a broad volume within a novel three-dimensional ordered porous medium, reconstructing flow at a micrometre characteristic length scale (Reynolds numbers << 1) via time-resolved microtomographic particle image velocimetry. Beyond a critical Weissenberg number of two we observe an elastic flow instability accompanied by an enhanced pressure drop with spectral characteristics typical of ET. Polymer chains in the ET flow state are advected along increasingly curved streamlines between pores such that they accumulate strain and generate a local flow instability evaluated per an established instability criterion based on local evaluation of elastic tensile stress and streamline curvature. The onset of ET leads to increased pore-scale resistance and positive feedback on upstream streamline curvature. ET is thus characterised by a continuous evolution between states of laminar and unstable flow: pores with unstable flow flood their adjacent peers and thus encourage straightened streamlines and flow stability across the array while positive feedback from flow resistance on streamline curvature results in the instability propagating upstream along the array. By employing a geometrically ordered medium we permit flow state communication between pores, yielding generalised insights highlighting the significance of spatial correlation and flow history, and thus provide new avenues for explaining the mechanisms of ET.