| Summary: | An inverted bottle empties in a time <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>T</mi><mrow><mi>e</mi><mo>,</mo><mn>0</mn></mrow></msub></semantics></math></inline-formula> through a process called “glugging”, whereby gas and liquid compete at the neck (of diameter <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>D</mi><mi>N</mi></msub></semantics></math></inline-formula>). In contrast, an open-top container empties in a much shorter time <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>T</mi><mi>e</mi></msub></semantics></math></inline-formula> through “jetting” due to the lack of gas–liquid competition. Experiments and theory demonstrate that, by introducing a perforation (diameter <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>d</mi><mi>p</mi></msub></semantics></math></inline-formula>), a bottle empties through glugging, jetting, or a combination of the two. For a certain range of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>d</mi><mi>p</mi></msub><mo>/</mo><msub><mi>D</mi><mi>N</mi></msub></mrow></semantics></math></inline-formula>, the perforation increases the emptying time, and a particular value of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>d</mi><mi>p</mi></msub><mo>/</mo><msub><mi>D</mi><mi>N</mi></msub></mrow></semantics></math></inline-formula> is associated with a maximum emptying time <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>T</mi><mrow><mi>e</mi><mo>,</mo><mi>m</mi><mi>a</mi><mi>x</mi></mrow></msub></semantics></math></inline-formula>. We show that the transition from jetting to glugging is initiated by the jet velocity reaching a low threshold, thereby allowing a slug of air entry into the neck that stops jetting and starts the glugging. Once initiated, the glugging proceeds as though there is no perforation. Experimental results covered a range of Eötvös numbers from <i>Eo</i>∼ 20–200 (equivalent to a range of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>D</mi><mi>N</mi></msub><mo>/</mo><msub><mi>L</mi><mi>c</mi></msub><mo>∼</mo></mrow></semantics></math></inline-formula> 4–15, where <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>L</mi><mi>c</mi></msub></semantics></math></inline-formula> is the capillary length). The phenomenon of bottle emptying with a perforation adds to the body of bottle literature, which has already considered the influence of shape, inclination, liquid properties, etc.
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