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Fingering dynamics driven by a precipitation reaction: Nonlinear simulations
Published in American Physical Society
2016
Volume: 93
   
Issue: 2
Abstract
A fingering instability can develop at the interface between two fluids when the more mobile fluid is injected into the less-mobile one. For example, viscous fingering appears when a less viscous (i.e., more mobile) fluid displaces a more viscous (and hence less mobile) one in a porous medium. Fingering can also be due to a local change in mobility arising when a precipitation reaction locally decreases the permeability. We numerically analyze the properties of the related precipitation fingering patterns occurring when an A+B→C chemical reaction takes place, where A and B are reactants in solution and C is a solid product. We show that, similarly to reactive viscous fingering patterns, the precipitation fingering structures differ depending on whether A invades B or vice versa. This asymmetry can be related to underlying asymmetric concentration profiles developing when diffusion coefficients or initial concentrations of the reactants differ. In contrast to reactive viscous fingering, however, precipitation fingering patterns appear at shorter time scales than viscous fingers because the solid product C has a diffusivity tending to zero which destabilizes the displacement. Moreover, contrary to reactive viscous fingering, the system is more unstable with regard to precipitation fingering when the high-concentrated solution is injected into the low-concentrated one or when the faster diffusing reactant displaces the slower diffusing one. © 2016 American Physical Society.
About the journal
JournalData powered by TypesetPhysical Review E
PublisherData powered by TypesetAmerican Physical Society
ISSN24700045
Open AccessYes
Concepts (12)
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    Chemical analysis
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    Diffusion in liquids
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    Porous materials
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    ASYMMETRIC CONCENTRATION
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    CONCENTRATED SOLUTION
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    FINGERING INSTABILITIES
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    FINGERING PATTERNS
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    Initial concentration
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    Nonlinear simulations
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    Precipitation reaction
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    Viscous fingering
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    Precipitation (chemical)