Numerical study of rising Taylor bubbles driven by buoyancy and additional pressure

The Taylor bubble driven by buoyancy and additional pressure is in a non-equilibrium state, which bubble and liquid flow have an accelerated tendency of rising, and the bubble behavior is significantly different with the Taylor bubble in stagnant liquid. In order to understand the dynamic properties of such bubbles, a numerical study was conducted using the coupled level-set and volume-of-fluid (CLSVOF) method combined with the stress-blended eddy simulation (SBES) model. The research results indicated that, due to the additional pressure, the difference between the bubble pressure head and the liquid column height is larger than zero, the pressure gradient force acting on the liquid column is greater than the force of gravity, this makes the bubble have an accelerating upward trend. The bubble shape and liquid film thickness are closely related to the relative bubble velocity, the correlation between dimensionless liquid film thickness and Reynolds number of relative bubble velocity was proposed. In addition, the article analyzed the influence mechanism of bubble shape, which is determined by the stress state of the fluid surrounding the bubble. Under the additional pressure, the axial stress on the bubble top increases significantly, while the radial stress remains almost invariable, which makes the bubble shape gradually become thinner.