Effect of chaotic advection generated by oscillatory flow on mixing-induced precipitation

Chaotic advection can be created by engineered sequence of extraction and injection of groundwater in aquifers and by creating an engineered oscillatory flow. It has been used in a wide range of applications, including enhancement of degradation during aquifer remediation, in-situ leaching of metals to enhance mining recovery, and dissipation of energy in geothermal systems. Most of these works are based on numerical simulations and little experimental evidence are reported in the literature. In this work, we analyze how an engineered oscillatory flow can favor mixing-induced precipitation, increasing the total amount and the extension of precipitation zone, with the objective to provide new corrective measures based on permeability reduction. For instance, one can isolate a target aquifer region hydraulically by creating an impervious barrier in the mixing zone. Laboratory experiments were used to study the effect of chaotic advection on mixing-induced precipitation. The experiments were performed in a transparent horizontal two-dimensional tank made of plexiglass filled with glass beads. In the experimental investigation, two different chemical solutions containing CaCl and NaCO3 were injected in separate inlet ports with different concentration. oscillatory flow was created by tuning the inflow rate, we analyze the effect of different injection rates on precipitation. As a result, a calcite precipitate layer with different width was formed between the individual solutions. Color tracer tests were injected before and after the experiment to visualize the impact of precipitation.