PARAMETERIZATION OF DRAG AND DISSOLUTION OF RISING CO_2 DROPS IN SEAWATER

摘要

An analysis of the dissolution and dynamics of a single CO_2 drop rising from 800 meters depth was made. The drop was simulated by a numerical model and theories of mass transfer and rise velocity were studied and compared to data from an ocean experiment. Hydrate is expected to reduce the mass transfer from the drop to the surrounding seawater. Common theory with a reduction factor of 2 matches the observed dissolution rate. This is compatible with laboratory results. Using a theory including the standard drag curve of rigid spheres did not fit the observed rise velocity of the hydrate-covered CO_2 drop. However an existing parameterization for drag of bubbles accounting for change of shape matched the observed drop velocity reasonably well. Numerical experiments with different drop sizes show that the choice of drag parameterization has a significant impact on the vertical distribution of dissolved CO_2.