Microfluidic observation of the onset of reactive‐infitration instability in an analog fracture

• Published in: Geophysical research letters 2016-07, Vol.43 (13), p.6907-6915
• Main Authors: Osselin, F., Kondratiuk, P., Budek, A., Cybulski, O., Garstecki, P., Szymczak, P.
• Format: Article
• Language: English
• Subjects: Advection; Analogs; Chemical Physics; Continental interfaces, environment; Diffusion; Dissolution; Dissolving; Distance; Dye dispersion; Flow rates; Flow velocity; fracture flow; Fracture mechanics; Fractures; Fronts; Geophysics; Gypsum; Infiltration; Instability; Microfluidics; Minerals; Physics; Plate tectonics; Plates (tectonics); Polycarbonate; reactive‐infiltration instability; Sciences of the Universe; Stability; Stability analysis; Wavelengths
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2016GL069261

Reactive‐infiltration instability plays an important role in many geophysical problems yet theoretical models have rarely been validated experimentally. We study the dissolution of an analog fracture in a simple microfluidic setup, with a gypsum block inserted in between two polycarbonate plates. By changing the flow rate and the distance between the plates, we are able to scan a relatively wide range of Péclet and Damkhöhler numbers, characterizing the relative magnitude of advection, diffusion, and reaction in the system. We quantify the characteristic initial wavelengths of the perturbed fronts during the onset of instability. The results agree well with theoretical predictions based on linear stability analysis, thus experimentally validating current reactive‐infiltration instability theory and opening new opportunities for experimental assessment of mineral reactivity. Key Points Microfluidic setup provides a controlled way of observing the reactive‐infiltration instability Experimentally measured instability wavelength compares favorably to the theoretical prediction This experimental setup can also be used to determine the intrinsic reaction rate of minerals