Interaction of two differently sized bubbles in a viscous liquid

Abstract

AbstractInteraction of two in‐line bubbles with different size in a viscous liquid is studied using volume‐of‐fluid method. Simulations are performed on initially spherical bubbles starting from rest. The influences of size ratio 0.5 ≤ R ≥ 1 and initial distance ratio 1.7 ≤ S ≥ 3 are investigated with fixed Eötvös number Eo = 50, Galilei number Ga = 100, density ratio η = 1,000, and viscosity ratio λ = 100. Two arrangement patterns are considered, the small‐big arrangement (SBA) and big‐small arrangement (BSA). Two distinct evolution regimes are defined: coalescence and penetration. The bubble‐bubble interaction is intensified by increasing R and decreasing S, promoting the possibility of coalescence. Penetration is more prone to occur in BSA than in SBA, and it is absent in BSA when R ≤ 0.625 regardless of S. The ascending velocity of the leading bubble (LB) is nearly independent of size ratio, initial distance ratio, and arrangement pattern, since the motion of the LB is little influenced by the trailing bubble (TB). Meanwhile, the ascending velocity of the TB increases with increasing R and decreasing S. The LB usually plays a dominant role in the interaction, especially in BSA.