Beverage industry to benefit from this IIT Roorkee work on emptying bottles faster

Bottle emptying is a phenomenon, most of us have observed while pouring a beverage.

A team of Indian researchers discovered how to make bottles empty faster, which can help chemical plants, apart from the beverage industry.

In a paper published in the journal Physics of Fluids on Tuesday, Arup Kumar Das, an assistant professor at the Indian Institute of Technology Roorkee and his doctoral student Lokesh Rohilla showed that the geometry of the bottle and thermophysical properties of the fluid play a role in reducing the time taken for emptying a bottle.

To understand this, the IIT Roorkee researchers explored the bottle-emptying phenomenon from the perspective of bubble dynamics on a commercial bottle using high-speed photography. Image analysis allowed them to conceptualize various parameters, such as liquid film thickness, bubble aspect ratio, rise velocity and bottle emptying modes.

What does the research look at?

Bubbles have been studied extensively for centuries. The growth dynamics of bubbles at the mouth of a bottle depend on the thermophysical properties of the fluid, the bottle geometry and its angle of inclination. These inextricably intertwined parameters have made bottle-emptying dynamics the next frontier for bubble physicists.

"Bubble dynamics inside the bottle are too complex to study, so we divided the bubble interfacial growth into different stages to comprehend them," said Rohilla in a statement.

It is well known that a bottle's emptying time is faster if you increase its angle of inclination. This increases what's known as bubble pinch off frequency, and the relative increment depends upon the thermophysical properties of the fluid.

Findings

"Our experiments suggest there is a critical angle of inclination, after which any further increase in the inclination of the bottle won't lead to further reduction in the bottle emptying time," said Rohilla. "This occurs due to the saturation of the voidage -- space occupied by air within liquid surrounding -- at the bottle's mouth with the angle of inclination."

Two distinct bottle-emptying modes found

Two distinct bottle-emptying modes were identified. In one mode, the discharge rate is increased due to a high frequency pinch off of air bubbles inside the bottle. In the other mode, it is caused by an increase in volume of the pinched-off bubble at a comparatively lower frequency.

"We can manipulate the bottle discharge pattern by manipulating bottle geometry," said Das. "An intuitive product-specific bottle design will enable better control of its discharge rate."

The beverage industry and chemical plants are among the applications that will benefit from a better understanding of bottle geometry.

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