School of Physics Spring Colloquium Series- Dr. Petia Vlahovska

Speaker: Dr. Petia Vlahovska

Host: Itamar Kolvin

Title: Collectives of motile particles: active matter meets fluid dynamics

Abstract: Active microparticles, such as swimming bacteria or self-propelled colloids, harvest energy from their environment and convert it into motion. Collectively, they spontaneously organize into intriguing large-scale dynamic structures. In this talk, I will present our efforts to design active particles that emulate bacterial locomotion and collective behavior. Our system consists of colloids that become motile via the Quincke instability, which is the spontaneous rotation of a dielectric sphere in a uniform electric field. In free space, Quincke rotors follow dynamics described by the Lorenz equations, making them a physical realization of Lorenz chaos. When confined to a surface, the spinning particles roll, forming a versatile model of self-propelled motion. I will show how these Quincke “rollers” can be engineered to exhibit run-and-tumble–like dynamics, mimicking swimmers such as E. coli. At the population level, these random walkers self-organize into collective states resembling those observed in bacterial suspensions, including dynamic clustering, mesoscale turbulence-like flows, and emergent multi-vortex structures. When confined within a droplet, Quincke rollers generate pronounced shape fluctuations and drive droplet motility resembling amoeboid crawling. I will highlight the central role of the fluid flows generated by the particles in shaping both the collective dynamics and the resulting droplet motion.

Bio: Petia M. Vlahovska is a Professor of Engineering Sciences and Applied Mathematics at Northwestern University. She received a PhD in Chemical Engineering from Yale University (2003) and MS in Chemistry from Sofia University, Bulgaria (1994). Her research encompasses fluid dynamics, soft matter physics, and cell biomechanics, driven by multidisciplinary challenges in materials science, cell and tissue engineering, robotics, neuromorphic engineering, and microgravity technologies. Dr. Vlahovska has been recognized by several awards, including NSF Trailblazer Engineering Impact Award, Guggenheim Fellowship, Humboldt Fellowship for Experienced Researchers (Germany), NSF CAREER Award, and David Crighton Fellowship.  Dr. Vlahovska is a Fellow of the American Physical Society (APS). She currently serves as an Associate Editor for the Journal of Fluid Mechanics, the new SIAM Journal on Life Sciences, and Secretary/Treasurer of the APS- Division of Fluid Dynamics.