MOTION OF INTERACTING GAS BUBBLES IN A VISCOUS LIQUID INCLUDING WALL EFFECTS AND EVAPORATION

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Abstract
The motion of single and multiple gas bubbles in an otherwise stationary liquid contained in a closed right vertical cylinder is investigated using a modified volume-of-fluid (VOF) method incorporating surface tension stresses. An isolated bubble was considered in a separate paper [4], where the initial bubble radius was small in comparison with that of the cylinder and watt effects were negligible. In this work the focus is on the interference effects during the motion of two initially spherical bubbles in a gravitational field, as well as the influence of the container wall on the bubble motion: the initial bubble diameter in the present study is more than half the cylinder diameter. The bubble size is also much larger than that required to satisfy the condition in which the gas can be treated as incompressible. In addition, the effect on bubble motion of the inclusion of evaporation at the gas-liquid interface as well as the bursting of a bubble through a five surface are considered. The modified VOF method used in this study is able to identify and physically treat features such as bubble deformation, cusp formation, breakup, and joining. Results are presented in a two-dimensional as well as a three-dimensional coordinate framework. The bubble motion and deformation are characterized by the Reynolds number, the Bond number, the density ratio, the viscosity ratio, the ratio of the cylinder radius to that of the initial bubble, and for interacting bubbles, the initial bubble separation.