Understanding and modeling the internal dynamics of an interface in reference to bubble dynamics

Gibbs was the first to represent a phase interface by a dividing surface. Here, we extend Gibbs' concept of dividing surface to encompass fluid fronts such as a material or phase interface, shock front, and contact line. This extension of Gibbs' dividng surface is defined as a mathematical hypersurface that has its own material properties and internal dynamics. This is different from the usual way of describing a fluid front as a mathematical boundary with no mass and hence, no dynamics. This fact allows it to be both kinematically and dynamically equivalent to the physical interface, thereby providing a more accurate representation. Here, we use the canonical example of bubble growth and collapse to highlight this difference and show the importance of accounting for the mass of the interface.