The dissolution of carbon dioxide into water has attracted significant attention for the modeling of air-sea gas exchange, carbon dioxide sequestration into porous aquifers, gas transport in bioreactors, and other applications. In nearly all circumstances, the surface of water is covered by surfactants, which make the gas-liquid interface behave elastically and exhibit surface shear viscosity.
Here, we visualize the transport and mixing of carbon dioxide across a monolayer interface in an axisymmetric system with inertia. To the left is a schematic of the set up. A rotating knife edge at the interface with negligible contact surface area takes advantage of the surface shear viscosity to drive a strong overturning flow in the bulk via viscous coupling.
When carbon dioxide is dissolved into water, this system has a forced convection nature, which further enhances transport of carbon dioxide into water. This transport leads to intense radial gradients in the dissolved carbon dioxide resulting in the baroclinic production of azimuthal vorticity that alters the underlying meridional flow further enhancing the mixing.
This visualization is of a numerical simulation obtained by solving the Navier-Stokes-Bousinessq equations, detailing the instability.