A numerical study on reaction-induced radial fingering instability

Vandita Sharma, Satyajit Pramanik, Ching-Yao Chen, Manoranjan Mishra*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

The dynamics of fronts is analysed numerically in a radial geometry. We are interested to understand miscible fingering instabilities when the simple chemical reaction changes the viscosity of the fluid locally and a non-monotonic viscosity profile with a global maximum or minimum is formed. We consider viscosity-matched reactants and generating a product having different viscosity than the reactants. Depending on the effect of on the viscosity relative to the reactants, different viscous fingering (VF) patterns are captured which are in good qualitative agreement with the existing radial experiments. We have found that, for a given chemical reaction rate, an unfavourable viscosity contrast is not always sufficient to trigger the instability. For every fixed Péclet number , these effects of chemical reaction on VF are summarized in the Damköhler number the log-mobility ratio parameter space that exhibits a stable region separating two unstable regions corresponding to the cases of more and less viscous product. Fixing , we determine -dependent critical log-mobility ratios and such that no VF is observable whenever . The effect of geometry is observable on the onset of instability, where we obtain significant differences from existing results in the rectilinear geometry.

Original languageEnglish
Pages (from-to)624-638
Number of pages15
JournalJournal of Fluid Mechanics
Volume862
DOIs
StatePublished - 10 Mar 2019

Keywords

  • fingering instability
  • laminar reacting flows
  • porous media

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