A predictive model for dissolution of stably trapped bubbles in corner cavities

Abstract

A predictive model was introduced to describe the dissolution of stably trapped bubbles in corner cavities of pipe systems. Numerical simulations were executed to obtain the Sherwood number, which describes the gas transfer in the liquid phase. Experiments were executed to validate the predictive model and numerically obtained Sherwood numbers. It is concluded that the most accurate way to describe the air-water interface is with a no-slip boundary condition due to the presence of surfactants which renders the interface to be immobile. It was experimentally and numerically demonstrated that the Sherwood number is constant for a given Schmidt number, bulk Reynolds number and geometry. A correlation between the bulk Reynolds number, vertical aspect ratio, Schmidt number and Sherwood number was found on the analysed range. The vertical aspect ratio represents the vertical cavity depth over the diameter of the cavity. The influence of the system pressure, geometry scale and Sherwood number on the mass transfer rate over the air-water interface was discussed. Special attention was given to the geometry scale and the resulting time needed for complete dissolution of the bubble. It was found that the time taken for complete dissolution is a quadratic function of the geometry scale.