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Experimental analysis of density fingering instability modified by precipitation
L Binda1, C El Hasi2, A Zalts2
1Grupo de Medios Porosos, Facultad de Ingeniería, Universidad de Buenos Aires, Av. Paseo Colón 850, C1063ACV Ciudad Autónoma de Buenos Aires, Argentina.
Chaos (Woodbury, N.Y.)
|June 4, 2017
Summary
Precipitate formation, like barium carbonate (BaCO3), impacts density-driven hydrodynamic instabilities. CO2 consumption for precipitate formation significantly reduces mixing zones, more than particle settling effects.
Area of Science:
- Fluid Dynamics
- Chemical Precipitation
- Geochemistry
Background:
- Density-driven hydrodynamic instabilities, such as Rayleigh-Taylor instabilities, are crucial in various natural and industrial processes.
- Precipitate formation can alter fluid properties and flow dynamics, influencing instability development.
- Understanding these effects is key for processes involving gas dissolution and precipitation in liquid phases.
Purpose of the Study:
- To investigate the influence of barium carbonate (BaCO3) precipitate formation on density-induced hydrodynamic instabilities.
- To determine whether precipitate formation or particle settling has a greater impact on mixing zone development.
- To analyze the nonlinear regime of instability with and without precipitate presence.
Main Methods:
- Simulating CO2 dissolution in aqueous BaCl2 to induce Rayleigh-Taylor instabilities and BaCO3 precipitation.
- Utilizing Particle Image Velocimetry (PIV) to track BaCO3 particles as tracers for flow visualization and velocity measurement.
- Varying CO2 partial pressure to assess its effect on mixing zone recovery.
Main Results:
- BaCO3 precipitate initially formed at the finger front, later settling and creating downward flow.
- Contrary to expectations, finger length decreased, indicating CO2 consumption for precipitation was the dominant factor in reducing the mixing zone.
- Increased CO2 availability (higher partial pressure) compensated for CO2 consumption, recovering mixing zone length.
- Mixing zone development reached steady states faster in the absence of precipitate.
Conclusions:
- CO2 consumption during BaCO3 precipitation plays a more significant role in limiting mixing zone development than particle settling-induced downward flow.
- The rate of mixing zone development is slower when precipitate is present.
- Controlling reactant availability (CO2 partial pressure) can mitigate the impact of precipitation on hydrodynamic instabilities.
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