Effect of viscosity and density ratios on two drops rising side by side

Abstract

In most of the industrial processes today we might have to deal with bubbly flows. The starting point to this problem is to find the interactions between a pair of bubbles. In this thesis the effect of viscosity and density ratios on a pair of rising bubbles is examined. The ranges of the viscosity and the density ratios are chosen such that they represent pairs of fluids which are commonly used in industries and households. To understand the dynamics of pair of bubbles rising inside quiescent liquid we compared them with the dynamics of a of single bubble rising in a liquid. Tripathi et al. [20] identified five different regimes which describe the dynamics of a rising bubble in a quiescent liquid. The region I corresponds to low inertial regime where an air bubble rises maintaining its azimuthal symmetry and the region III corresponds to high inertial regime where the motion of a rising air bubble is chaotic. In this thesis the effect of the viscosity ratio and the density ratios on two bubbles rising side by side are found in region I and region III corresponding to the rise dynamics of a single bubble. Further to completely analyze the dynamics of pair of bubbles we plotted shapes, trajectories, aspect ratios, velocity contours and voricity of the two-bubbles over a wide range of the viscosity and density ratios(ranging from gas-liquid to liquid-liquid systems).