Ocean-atmosphere fluxes play a critical role in the evolution of climate. A better and more quantitative understanding of the physical mechanisms governing the exchanges of mass and gases across the air-water interface is strongly needed.
The breaking of ocean waves through the formation of the underwater bubbles provides the most significant contribution to the exchange process.
Whereas the exchange is governed by the dynamics of the air-water interface and the turbulent flow nearby, such aspects are not analyzed in detail when modelling the exchange processes in climatology or weather studies.
All those effects are characterized by a gas transfer velocity Kw, which is inherently approximate. A more accurate estimate of the exchange processes requires a detailed description of the atmospheric stability, wind fetch, sea state, breaking waves, white caps, bubble transport, rain, and the presence of surfactants.
Within this context, through a series of Direct Numerical Simulation(DNS) of an incompressible multiphase flow, we want to improve the model to estimate the gas transfer velocity Kw of CO2 under-sea.
In order to get this, the dynamics of a swarm of large and deformable bubbles injected into a turbulent channel flow is studied, and the mass transfer of CO2from the bubbles to the surrounding liquid is going to be analyzed.
Simone Di Giorgio, Institute of Marine Engineering - CNR - Italy