The Emptying of a Perforated Bottle

Bottle emptying, characterized by the familiar “glugging” of the gas and liquid flows at the neck, has previously been explored. Studies in the literature have considered the influence of bottle shape, size, inclination, and fluid properties. We have investigated an interesting scenario in which introducing a miniscule perforation, i.e., a hole typically 5% of the bottle neck diameter, can dramatically alter emptying. We report on experiments showing that perforated bottles emptying through glugging (being unaffected by the perforation in any observable way), jetting (when the perforation is large enough to allow full venting and only liquid outflow from the neck), or a combination of jetting that transitions to glugging sometime during the course of emptying. For a bottle with fixed shape and size, perforation size dictates the emptying mechanism. A combination of jetting and glugging is always found to yield emptying times exceeding the non-perforated case (glugging only). The perforation size causing maximum emptying time, and the emptying time increase, is correlated to the neck diameter. To complement our experiments, we theoretically model the emptying of a perforated bottle using a combination of existing glugging theory and single-phase flow (for the jetting regime).