Direct numerical simulation of carbon-dioxide gas absorption caused by turbulent free surface flow

Abstract

The turbulent behavior of liquid and gas flows at a free surface is not very well understood in comparison with that of the motions at the solid boundary. In the present study, the DNS for the turbulent free surface flow with a shear wind has been carried out by means of a coupled gas–liquid flow solution procedure, i.e., multi-interface and advection and reconstruction solver (MARS) developed by one of the authors. Henry's law is applied to the evaluation of a saturated gas concentration at the free surface caused by the carbon-dioxide gas absorption. Resulting from the present DNS of turbulent free surface flow with carbon-dioxide gas transfer at the gas–water interface, the mean and root-mean-square distributions of velocity, pressure and concentration and their fluctuations throughout both the gas and liquid flow fields are obtained and compared with the experimental data. Finally, an exchange coefficient of carbon-dioxide gas at the turbulent free surface estimated in this study is in good agreement with the existing experimental and sea-measurement data.