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Viscous Fingering Induced by a pH-Sensitive Clock Reaction
D M Escala1, A De Wit2, J Carballido-Landeira3
1Group of Nonlinear Physics , Universidade de Santiago de Compostela , E-15782 Santiago de Compostela , Spain.
Abstract:
A pH-changing clock chemical system, also known to induce changes in viscosity, is shown experimentally to induce a viscous fingering instability during the displacement of reactive solutions in a Hele-Shaw cell. Specifically, a low-viscosity solution of formaldehyde is displaced by a more viscous solution of sulfite and of a pH-sensitive poly(acrylic acid) polymer. The pH change triggered by the formaldehyde-sulfite clock reaction in the reactive contact zone between the two solutions affects the polymer and induces a local increase of the viscosity that destabilizes the displacement via a viscous fingering instability. The influence of changes in the chemical parameters on this fingering instability is analyzed using different techniques and the results are compared with numerical simulations.
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