On the choice of analogue fluids in CO2 convective dissolution experiments

Mixtures of ethylene glycol and methanol (EG‐MeOH) have been used as an analogue system (i.e., EG‐MeOH/water) in recent experiments in the context of convective dissolution of CO2 in deep saline aquifers. We have conducted a linear stability analysis of a gravitationally unstable diffusive boundary...

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Bibliographic Details
Published in:Water resources research 2016-06, Vol.52 (6), p.4458-4468
Main Authors: Jafari Raad, Seyed Mostafa, Emami‐Meybodi, Hamid, Hassanzadeh, Hassan
Format: Article
Language:English
Subjects:
analogue fluids
Aquifers
Boundary layer stability
Boundary layers
Buoyancy
Carbon dioxide
CO2 storage
Computational fluid dynamics
Computer simulation
convective dissolution
Convective mixing
deep saline aquifers
Direct numerical simulation
Dissolution
Dissolving
Dynamic stability
Dynamical systems
Dynamics
Ethene
Ethylene
Ethylene glycol
Evolution
Experiments
Fluids
Instability
Mathematical models
Methanol
Numerical simulations
Rayleigh number
Simulation
Stability analysis
Water
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Summary:Mixtures of ethylene glycol and methanol (EG‐MeOH) have been used as an analogue system (i.e., EG‐MeOH/water) in recent experiments in the context of convective dissolution of CO2 in deep saline aquifers. We have conducted a linear stability analysis of a gravitationally unstable diffusive boundary layer as well as direct numerical simulation of convective mixing involved in dissolution of EG‐MeOH species in water. We provide new evidences that EG‐MeOH does not resemble the dynamics of convective instabilities and subsequent mixing associated with dissolution of CO2 in water. It is found that there are fundamental differences in the evolution of the buoyancy‐driven instability and dynamics of convective mixing between CO2/water and a typical EG‐MeOH/water analogue system. Our results show that for a constant Rayleigh number, the onset of convective instabilities for EG‐MeOH/water can be different by an order of magnitude as compared with CO2/water. In addition, EG‐MeOH/water system reveals different dynamics associated with the convective mixing as compared to CO2/water system. This study improves our understanding of the instability behavior of analogue systems, their proper selection, and motivates further experiments. Key Points EG‐MeOH/water mixture does not mimic hydrodynamic stability of CO2/water system Shape of base‐state density profile has a great impact on the onset of convective instabilities Onset of instabilities varies by an order depending on composition of EG in EG‐MeOH solution
ISSN:0043-1397
1944-7973
DOI:10.1002/2015WR018040