The Impact of Container Elasticity on Fluid Drainage

As Rohit Velankar, a senior at Fox Chapel Area High School, poured juice into a glass, he began to notice the rhythmic sound of “glug, glug, glug” flexing the walls of the carton. This seemingly insignificant moment sparked his curiosity about how a container’s elasticity could potentially affect the way fluids are drained. Initially, this question was meant for a science fair project, but it evolved into something much greater when he enlisted the help of his father, Sachin Velankar, a professor of chemical and petroleum engineering at the University of Pittsburgh Swanson School of Engineering. Together, they conducted experiments in the family’s basement, leading to the publication of their first collaborative paper.

Their research, which was published in the journal Physics of Fluids, showcased Rohit’s initial discovery that deli containers with rubber lids emptied at a faster rate compared to those with plastic lids. According to Sachin Velankar, the phenomenon of “glugging” occurs due to the decreasing pressure within the bottle as the fluid exits. This led the Velankars to hypothesize that highly flexible containers, such as IV fluid bags or boxed wine, might be capable of dispensing fluid without experiencing glugs. However, they realized that there are other types of flexible bottles on the market, each with varying levels of elasticity that could impact drainage efficiency.

To further explore this concept, the father-son duo crafted their own acrylic bottles with rubber lids using resources available at Fox Chapel Area High School’s makerspace. By incorporating a sensor near the bottom hole of each bottle to measure pressure oscillations during drainage, the Velankars were able to simulate different levels of flexibility by adjusting the hole diameter. Their experiments conclusively demonstrated that flexible bottles do indeed drain faster, albeit with larger and less frequent glugs. This groundbreaking discovery not only sheds light on the physics behind fluid dynamics but also underscores the importance of container design in everyday applications.

The collaborative efforts of Rohit and Sachin Velankar have not only resulted in a fascinating research paper but have also opened up new avenues for exploring the impact of container elasticity on fluid drainage. This innovative study serves as a testament to the power of curiosity and scientific inquiry in uncovering the hidden mysteries of everyday phenomena.