Reactive-infiltration instability in radial geometry: From dissolution fingers to star patterns

Area of Science:

• Geochemistry
• Fluid Dynamics
• Materials Science

Background:

• Chemical erosion of porous media is crucial in various geological and industrial processes.
• Understanding fluid infiltration dynamics is key to predicting medium alteration.
• Thin-front approximations simplify complex reactive flow phenomena.

Purpose of the Study:

• To investigate the instability of a reactive fluid front infiltrating a porous medium.
• To analyze the influence of flow rate on front stability in radial geometry.
• To compare reactive-infiltration instability with other known instabilities like Saffman-Taylor.

Main Methods:

• Mathematical modeling of reactive fluid flow in a porous medium.
• Analysis of the thin-front limit where front width is negligible.
• Comparison of parameter spaces for reactive-infiltration and Saffman-Taylor instabilities.

Main Results:

• The advancing reactive front in radial geometry becomes unstable only above a critical flow rate.
• A stable region in parameter space exists for reactive-infiltration, unlike Saffman-Taylor instability.
• Similarities were found between reactive-infiltration and heat transfer instabilities, such as those forming star-like patterns on frozen lakes.

Conclusions:

• Flow rate is a critical parameter determining the stability of reactive infiltration fronts.
• Reactive-infiltration instability exhibits distinct behavior compared to Saffman-Taylor instability.
• The study provides insights into pattern formation mechanisms driven by reactive flow and heat transfer.