Liquiddrop

Liquiddrop is a term used in fluid dynamics and related fields to denote a small, cohesive drop of liquid that can be treated as a discrete object for study. In experimental and computational contexts, a liquiddrop serves as a model system to examine interfacial phenomena, drop formation, breakup, evaporation, and interactions with surfaces or external fields. The term is not tied to a single standard definition and may be used variably to emphasize the droplet’s particulate character in a continuous medium.

Typical liquiddrops range from tens of micrometers to a few millimeters in diameter, depending on the liquid and generation method. Their behavior is governed by surface tension, density, and viscosity. Forces acting on a drop include gravity, drag, and capillary forces; the interface may deform under external flow, electric fields, or thermal gradients. Surface tension gradients can drive Marangoni flows inside the drop, producing internal circulation.

Formation and observation: Liquiddrops are produced by atomization, microdrop jetting, dripping, or nozzle-based dispensers. They are tracked with high-speed videography, laser-induced fluorescence, or interferometric techniques. In simulations, liquids are often modelled with volume-of-fluid, phase-field, or level-set methods, using dimensionless groups such as the Reynolds, Weber, and Bond numbers to characterize regimes of behavior like deposition, splashing, breakup, or coalescence.

Applications: The concept is central to inkjet printing, spray coating, aerosol science, and microfluidics, where precise control of droplet size, trajectory, and evaporation is important. Liquiddrop models also aid in understanding droplet evaporation dynamics, contact-line pinning, and droplet spreading on solid surfaces.

See also: droplet, surface tension, Marangoni effect, microfluidics, atomization, inkjet printing.