As Rohit Velankar, a senior at Fox Chapel Area High School, poured juice into a glass, he noticed the rhythmic “glug, glug, glug” flexing the walls of the carton. Intrigued by this phenomenon, he began exploring whether a container’s elasticity affects the way its contents drain. What started as a simple science fair project quickly evolved into a collaborative effort between Rohit and his father, Sachin Velankar, a professor of chemical and petroleum engineering at the University of Pittsburgh Swanson School of Engineering.
Setting up their experiment in the basement, the father-son duo embarked on a journey to uncover the secrets of glugging. Their joint efforts culminated in the publication of their first paper together in the prestigious journal Physics of Fluids. According to Sachin Velankar, the project took on a life of its own as they delved deeper into the intricacies of fluid dynamics. “We were both committed to seeing it through to the end once we started the experiments,” he remarked.
Rohit’s initial experiments revealed that deli containers with rubber lids drained faster than those with plastic lids, shedding light on the glugging phenomenon. Sachin Velankar explained, “Glugging occurs when the exiting liquid reduces the pressure within the bottle. Containers with high flexibility, such as IV fluid bags or boxed wine, can dispense fluid without glugging. However, the elasticity of other types of bottles likely plays a role in their draining behavior.”
To further explore the impact of elasticity on drainage, the Velankars crafted acrylic bottles with rubber lids using resources available at Fox Chapel Area High School’s makerspace. By installing sensors near the bottom of each bottle to monitor pressure oscillations during glugging, they were able to simulate different levels of flexibility. Their experiments confirmed that flexible bottles drained at a faster rate, albeit with larger and less frequent glugs.
The collaborative efforts of Rohit and Sachin Velankar shed light on the role of elasticity in the glugging phenomenon. Their innovative approach to scientific inquiry not only deepened their understanding of fluid dynamics but also exemplified the power of curiosity and collaboration in research.