Wine exiting a blue bottle, with air being drawn into the neck, and the bubble of the previous glug to the top-right of the body Glugging (also referred to as "the glug-glug process") is the physical phenomenon which occurs when a liquid is poured rapidly from a vessel with a narrow opening, such as a bottle. It is a facet of fluid dynamics. As liquid is poured from a bottle, the

air pressure Atmospheric pressure, also known as barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1013.25 millibars ...

in the bottle is lowered, and air at higher pressure from outside the bottle is forced into the bottle, in the form of a

bubble Bubble, Bubbles or The Bubble may refer to: Common uses * Bubble (physics), a globule of one substance in another, usually gas in a liquid ** Soap bubble * Economic bubble, a situation where asset prices are much higher than underlying funda ...

, impeding the flow of liquid. Once the bubble enters, more liquid escapes, and the process is repeated. The reciprocal action of glugging creates a rhythmic sound. The English word "glug" is onomatopoeic, describing this sound. Onomatopoeias in other languages include (German).

Academic paper Academic publishing is the subfield of publishing which distributes academic research and scholarship. Most academic work is published in academic journal articles, books or theses. The part of academic written output that is not formally pub ...

s have been written about the

physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...

of glugging, and about the impact of glugging sounds on consumers' perception of products such as

wine Wine is an alcoholic drink typically made from fermented grapes. Yeast consumes the sugar in the grapes and converts it to ethanol and carbon dioxide, releasing heat in the process. Different varieties of grapes and strains of yeasts are m ...

. Research into glugging has been done using

high-speed photography High-speed photography is the science of taking pictures of very fast phenomena. In 1948, the Society of Motion Picture and Television Engineers (SMPTE) defined high-speed photography as any set of photographs captured by a camera capable of 69 ...

. Factors which affect glugging are the

viscosity The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the inte ...

of the liquid, its

carbonation Carbonation is the chemical reaction of carbon dioxide to give carbonates, bicarbonates, and carbonic acid. In chemistry, the term is sometimes used in place of carboxylation, which refers to the formation of carboxylic acids. In inorganic ch ...

, the size and shape of the container's neck and its opening (collectively referred to as "bottle geometry"), the angle at which the container is held, and the ratio of air to liquid in the bottle (which means that the rate and the sound of the glugging changes as the bottle empties).

References

{{Reflist Fluid dynamics Food science