Title : Recent investigations on bubble dynamics
Contact : Giovanni Ghigliotti
Abstract : The seminar addresses two topics related to bubble dynamics. The first one is about skirt bubbles. For viscous liquids and large bubble, a thin layer of fluid, commonly referred to as a “skirt†, can be observed issuing from the rim of bubbles. First reported for drops by Thomson and Newall (1885), the appearance of skirts requires a sufficiently viscous continuous phase. Different theories have been proposed for the skirt description. The significant differences between experimental observations and proposed theories have motivated this work. Direct numerical simulations of skirt bubbles are presented and investigated to clarify skirt bubble dynamics. In the second part of the seminar, the stability of bubble chain is discussed. For example, bubbles appear when a carbonated drink is poured in a glass. Very stable bubble chains are clearly observed in champagne, showing an almost straight line from microscopic nucleation sites on the glass surface from which they are continuously formed. In some other drinks such as soda, such chains are not straight (not stable). Considering pair interactions for spherical clean bubbles, bubble chains should not be stable which contradicts some observations. The aim of this work is to explain the condition of stability of bubble chains. For this purpose, experiments and direct numerical simulation are presented.