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D M Escala1, A De Wit2, J Carballido-Landeira3

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Summary
This summary is machine-generated.

A chemical clock reaction triggers viscosity changes, causing viscous fingering instability in fluid displacement. This study explores how pH shifts in reactive solutions impact this phenomenon in Hele-Shaw cells.

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Area of Science:

  • Chemical Engineering
  • Fluid Dynamics
  • Polymer Science

Background:

  • Viscous fingering is a fluid instability occurring at interfaces between fluids of different viscosities.
  • Chemical reactions can alter fluid properties, potentially influencing interfacial instabilities.
  • Hele-Shaw cells are standard experimental tools for studying fluid dynamics and instabilities.

Purpose of the Study:

  • To experimentally demonstrate viscous fingering instability induced by a pH-changing clock chemical system.
  • To investigate how changes in viscosity, driven by a chemical reaction, destabilize fluid displacement.
  • To analyze the impact of chemical parameters on fingering instability and compare with simulations.

Main Methods:

  • Utilizing a Hele-Shaw cell to observe fluid displacement.
  • Employing a formaldehyde-sulfite clock reaction to induce pH changes.
  • Displacing a low-viscosity formaldehyde solution with a more viscous sulfite and poly(acrylic acid) solution.
  • Analyzing the influence of chemical parameters and comparing experimental results with numerical simulations.

Main Results:

  • A pH-changing clock chemical system was experimentally shown to induce viscous fingering instability.
  • The chemical reaction in the contact zone increased local viscosity, destabilizing the displacement.
  • Observed fingering instability was influenced by variations in chemical parameters.

Conclusions:

  • pH-triggered viscosity changes in reactive solutions can induce viscous fingering instability.
  • The formaldehyde-sulfite clock reaction provides a mechanism to control and study this instability.
  • Experimental findings align with numerical simulations, validating the model.