The Science Behind Fluid Draining: A Father-Son Experiment

As a senior at Fox Chapel Area High School, Rohit Velankar found himself pondering the peculiar rhythmic sound of liquid pouring into a glass. This simple act of pouring juice sparked his curiosity about whether a container’s elasticity had any influence on the way its fluid drained. What started as a science fair project soon turned into a collaborative experiment with his father, Sachin Velankar, a professor of chemical and petroleum engineering at the University of Pittsburgh Swanson School of Engineering.

Teaming up with his father, they conducted experiments in the basement of their home to delve deeper into the dynamics of fluid draining. Their collaborative efforts resulted in their first published paper together in the journal Physics of Fluids. Sachin Velankar reflected on the project, stating, “I became quite invested in the project myself as a scientist. We agreed that once we started on the experiments, we’d need to take it to completion.”

Rohit’s initial experiments revealed that deli containers with rubber lids drained faster than those with plastic lids, leading to the phenomenon of “glugging.” According to Velankar, the presence of glugging is attributed to the decreasing pressure within the container as fluid exits. The experiment also involved creating custom acrylic bottles with rubber lids in a makerspace at Fox Chapel Area High School. Placing a sensor near the hole at the bottom of each bottle allowed the Velankars to measure pressure oscillations with each glug.

Through their experiments, the Velankars were able to simulate flexibility by adjusting the diameter of the hole in the bottles. This adjustment confirmed their hypothesis that flexible bottles indeed drain faster, albeit with bigger and more infrequent glugs. The study shed light on the role of elasticity in fluid dynamics, paving the way for further research in the field.

Rohit Velankar’s curiosity and scientific inquiry, combined with the expertise of his father, led to a fascinating exploration of fluid dynamics. Their collaborative efforts not only resulted in a published paper but also deepened their bond as father and son through a shared passion for scientific exploration.