標題: A numerical study on reaction-induced radial fingering instability
作者: Sharma, Vandita
Pramanik, Satyajit
Chen, Ching-Yao
Mishra, Manoranjan
機械工程學系
Department of Mechanical Engineering
關鍵字: fingering instability;laminar reacting flows;porous media
公開日期: 11-Jan-2019
摘要: The dynamics of A + B -> C 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 A and B generating a product C having different viscosity than the reactants. Depending on the effect of C 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 Peclet number (Pe), these effects of chemical reaction on VF are summarized in the Damkohler number (Da) - the log-mobility ratio (R-c) parameter space that exhibits a stable region separating two unstable regions corresponding to the cases of more and less viscous product. Fixing Pe, we determine Da-dependent critical log-mobility ratios R-c(+) and R-c(-) such that no VF is observable whenever R-c(-) <= R-c <= R-c(+). The effect of geometry is observable on the onset of instability, where we obtain significant differences from existing results in the rectilinear geometry.
URI: http://dx.doi.org/10.1017/jfm.2018.963
http://hdl.handle.net/11536/148713
ISSN: 0022-1120
DOI: 10.1017/jfm.2018.963
期刊: JOURNAL OF FLUID MECHANICS
Volume: 862
起始頁: 624
結束頁: 638
Appears in Collections:Articles