Physical Review Journal Club: Motility and interfacial instability of confined chemically active droplets
Monday October 24, 2026
9:39 ET
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The Physical Review Journal Club returns with a discussion with author Pawan Kumar (Indian Institute of Technology Kanpur), presenting their recently published Physical Review Fluids article, “Motility and interfacial instability of confined chemically active droplets.”
Microorganisms squeezing through narrow spaces often wiggle their bodies to keep moving. Artificial active droplets can also travel through channels narrower than themselves, but until now they were thought to do so with a fixed, steady shape.
Using experiments on self-propelled liquid-crystal droplets in surfactant solutions, the authors show that adding solutes or raising the surfactant concentration makes the droplet interface start to undulate. Changing the confinement switches these undulations from both sides of the droplet to a single travelling wave on one side. A linear stability analysis identifies the Yih–Marangoni instability as the cause. This reveals a previously unrecognized mode of adaptive locomotion in confined active matter.
After the presentation, the authors will answer questions from the audience in a live Q&A session, moderated by PRFluids Editorial Board Member Ho-Young Kim (Seoul National University)
Read ahead:
Motility and interfacial instability of confined chemically active droplets
Kumar, P., Ashraf, S., Tiwari, N., Pillai, D. and Mangal, R.
Physical Review Fluids 11, 094005 (2026)
