Drop and bubble phenomena

Drop and bubble phenomena are the formation, motion, deformation, breakup, and coalescence of liquid drops and gas bubbles in fluids. Their behavior reflects the competition among inertia, viscosity, buoyancy, and surface tension.

Connect

Surface tension: The tendency of a liquid interface to minimize its area because molecules at the surface experience unbalanced cohesive forces. It resists deformation and breakup while driving small drops and bubbles toward spherical shapes.
Interfacial tension: The free energy per unit area of a boundary between two fluid phases. It determines the energetic cost of creating and stretching drop and bubble surfaces.
Spray formation: The production of a dispersed cloud of liquid droplets from a bulk liquid or liquid jet. Atomization converts liquid streams into drops through deformation and breakup.
Rigid-sphere drag: The hydrodynamic resistance experienced by a solid sphere moving through a fluid. A clean bubble can have lower drag because its interface permits tangential fluid motion.
Stokes rise of a bubble: The slow ascent of a small spherical bubble in a viscous fluid at very low Reynolds number. This limiting case isolates buoyancy and viscous drag before inertial effects matter.
Capillary number: A dimensionless ratio of viscous forces to surface tension forces in an interfacial flow. It predicts when flow-induced stresses overcome surface tension and deform a drop.
Viscosity: A measure of a fluid's resistance to deformation and flow. It damps internal circulation and shape changes in moving drops and bubbles.
Emulsion: A mixture in which droplets of one immiscible liquid are dispersed in another. Drop breakup and coalescence determine emulsion size, stability, and texture.
Stokes flow: A creeping-flow regime in which viscous forces dominate inertia. Its idealized motion differs from inertial regimes where wakes and strong deformation emerge.
Taylor bubble: An elongated gas bubble that nearly fills a narrow tube, with a liquid film around it. Confinement produces a distinctive long-bubble shape and coupled film flow.