#SoCaltech: Rahul Arun
“I first visited Caltech after being accepted to the undergraduate program and, having grown up in Illinois, told my dad that I was never shoveling snow again. I knew I wanted to study fluid mechanics after falling in love with its broad-ranging applications—from viruses to airplanes—in high school. My undergraduate years were filled with new and varied experiences: fluidized sands, viscous fingers, resolvent analyses, and elliptic instabilities.
Staying at Caltech for graduate school allowed me to pursue deep questions about turbulent flows while also exploring how they shape less-familiar disciplines. Since I had already completed much of the aerospace curriculum, my advisors challenged me to propose custom coursework that would satisfy the degree requirements. Using that opportunity to immerse myself in geophysical fluid dynamics was a defining moment of my graduate career. The cross-departmental courses I took exposed me to a side of our fluid world that I hadn’t fully appreciated before. They also set the foundation for my current work as a Stanback Postdoctoral Fellow, where I’m broadly exploring models of geophysical turbulence.
What I like about turbulence is it's really complex but not hopelessly so. It’s visually appealing, it’s mentally stimulating, and it's everywhere. Turbulence holds the key to modern mysteries of Earth’s atmosphere, ocean, and outer core. But it is also central to engineering efforts, from ships to pipes to even golf balls. That combination of depth and breadth really appeals to me. It means there’s always something new to learn.
The last nine years at Caltech have consistently surprised me with new people, perspectives, and puzzles. It’s hard to imagine anywhere else where I could go from engineering to geophysics, tabletop experiments to massive simulations, and the pool to the classroom within a five-minute walk. I’m struck by how this small institution has managed to broaden my horizons so much. Caltech has taught me that there’s always more than meets the eye, leaving me with an appreciation for my surroundings and a curiosity to last a lifetime.”
Rahul Arun (BS ’21, PhD ’25) is a Foster and Coco Stanback Prize Postdoctoral Fellow in the Division of Geological and Planetary Sciences. He received his BS in mechanical engineering with an aerospace minor in 2021 and his PhD in aeronautics in 2025—all from Caltech. He played for and later coached Caltech’s water polo team and, in his free time, enjoys walking his dog, Frankie, around campus and cleaning up trash along the Angeles Crest Highway. This summer, Arun joins the Center for Turbulence Research at Stanford to continue unraveling the complexity of turbulent flows.
#SoCaltech is an occasional series celebrating the diverse individuals who give Caltech its spirit of excellence, ambition, and ingenuity. Know someone we should profile? Send nominations to magazine@caltech.edu.