Mixing by polymers: experimental test of decay regime of mixing

Abstract

By using high molecular weight fluorescent passive tracers with different diffusion coefficients and by changing the fluid velocity we study dependence of a characteristic mixing length on the Peclet number, $Pe$, which controls the mixing efficiency. The mixing length is found to be related to $Pe$ by a power law, $L_{mix}\propto P{e}^{0.26\pm 0.01}$, and increases faster than expected for an unbounded chaotic flow. Role of the boundaries in the mixing length abnormal growth is clarified. The experimental findings are in a good quantitative agreement with the recent theoretical predictions.

arXiv comment4 pages,5 figures. accepted for publication in PRL

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• Measures of mixing quality in open flows with chaotic advection
• Harnessing elastic instabilities for enhanced mixing and reaction kinetics in porous media
• New directions and perspectives in elastic instability and turbulence in various viscoelastic flow geometries without inertia
• Oscillatory elastic instabilities in an extensional viscoelastic flow
• Scalar decay in a three-dimensional chaotic flow
• Flow pattern transition accompanied with sudden growth of flow resistance in two-dimensional curvilinear viscoelastic flows
• Elastic waves in a Hele-Shaw cell with a co-moving Kelvin-Helmholtz-like parallel shear flow
• Pressure measurements in an elastically turbulent co-moving Kelvin-Helmholtz-like shear flow inside a straight Hele-Shaw cell