Vatsal Sanjay

Push a long bubble slowly through a liquid-filled tube and it leaves a wall film, h/R ≈ 1.34 Ca^(2/3), Ca = μU/γ, U = bubble speed (Bretherton 1961). A capillary-pressure gradient near the nose balances viscous drag, so doubling U thickens the film about 1.6 times. youtu.be/_FGKC7hdaBU

#RésultatScientifique 🔎 | Filaments sous écoulement oscillant : une danse entre ordre et chaos 🔬 @pmmh-lab.bsky.social 🤝 @cnrs.fr @espciparispsl.bsky.social @sorbonne-universite.fr @upcite.bsky.social 📍 @cnrs-paris.bsky.social ➡️ urlr.me/dfBqs6

🚨New Preprint with @zwickergroup.bsky.social ! Phase-separated condensates 🫧 often encounter compositional gradients. We show that these gradients generically lead to surface-tension-driven propulsion even in the absence of surfactants. 📃 arxiv.org/abs/2609.24529

At first glance, the dune field of Lençóis Maranhenses National Park in northeastern Brazil looks like a desert. But this area's rainfall tops 50 inches a year, exceeding Seattle's typical amount. https://fyfluiddynamics.com/?p=33887

🔬 Fluid Inspirations #7 Theme: Transport and turbulent mixing Experimental Quantification of Airborne Odor Plumes. 🔗 gfm.aps.org/meetings/dfd... Source: APS Gallery of Fluid Motion 2025 – Video V041 #TransportPhenomena #TurbulenceResearch #FlowVisualization #AerosolScience #FluidMechanics

🌀 A tabletop experiment that uses a classical water vortex provides the first direct observation of Kelvin-wave turbulence, confirming a decades-old theory of how turbulence decays in quantum fluids. Read more: https://go.aps.org/4yGa4So

Wildfires can generate their own thunderstorms through pyrocumulonimbus clouds. These clouds can have an outsized impact on the stratosphere, too, injecting smoke and particulates that can linger for years to come. https://fyfluiddynamics.com/?p=33880

When a heavier fluid sits atop a lighter one, the interface between them can be unstable. This means that even a very slight disturbance will be enough to cause fingers of dense (dark) fluid to sink while fingers of the lighter (white) fluid rise. https://fyfluiddynamics.com/?p=12166

New images from our most powerful solar telescope have finally revealed a phenomenon that's long been predicted: Kelvin-Helmholtz waves on the Sun's photosphere. https://fyfluiddynamics.com/?p=32451

Sperm whales like to nap under the water and away from the waves. They seem to do this in a vertical, head-up orientation. But how do they keep from bobbing up? https://fyfluiddynamics.com/?p=32403

This timelapse from photographer Mike Olbinski shows a supercell thunderstorm that developed over Colorado and headed to Nebraska. The churning convection of the early storm makes for a dramatic backdrop to stormcloud's growing rotation. https://fyfluiddynamics.com/?p=30985

We're most familiar with the bright, forking lightning bolts that stretch from thunderstorms toward the ground, but there are even more types of lightning. Pictured here is a gigantic jet, a relatively recently-identified atmospheric phenomenon. https://fyfluiddynamics.com/?p=32012

Drops and bubbles both approach a finite-time fluid singularity as they pinch off. Add a little polymer, and the apparent symmetry breaks: the drop arrests into a thread, while the bubble still pinches. doi.org/10.1103/5sp3... @durham.ac.uk @durhamphysics.bsky.social @poftwente.bsky.social

@durhamphysics.bsky.social Welcome to @bsky.app ❤️

New paper by Jamie McLauchlan, working with Anton Souslov in Cambridge, and Jim Walker and Jonathan Reid in Bristol (and others, including us) - with a very cool combination of state-of-the-art experiments with theory: what happens when aerosol droplets hit surfaces? www.pnas.org/doi/10.1073/...

Watch the never-boring Pepijn Hoekstra explaining our work on #clogging from our labs! @utwente.bsky.social www.youtube.com/shorts/ZYHiE...

🎉 Congratulations to Dr. Jochem Meijer for winning the KIVI Hoogendoorn Fluid Mechanics Award 2024! His thesis "Particles, drops, and bubbles in gradient fields" was recognized as the best PhD thesis of 2023-24. Supervised by @detleflohse.bsky.social 👏 #FluidMechanics #PhD​​​​​​​​​​​​​​​​

@jnandeep.bsky.social (@poftwente.bsky.social) discussing his master thesis project on singularities with surfactants at the Max Planck meeting. How do surfactants influence coalescence of sessile drops? Teaser talk as Jnan explores the different dynamics across the Peclet-Marangoni parameter space

Introducing CyberDiver! This new untethered robotic device is capable of actively controlling impact forces and splash dynamics during water entry. arxiv.org/abs/2503.20702 Design source files: github.com/harrislab-br... Work led by #harrislab PhD student John.

This very cool paper, and Carl's very nice short thread describing the value of basic research in biology, may be of interest to @thecopperdoctor.bsky.social @oneofmanychris.bsky.social and others.

So inspiring to hear my mentor, Detlef Lohse (@poftwente.bsky.social), share his scientific journey in this @thelhseries.bsky.social! His thoughts on curiosity, mentorship, and the "puzzle solving" joy of science resonate deeply. A must-watch! Always so much to learn. bit.ly/3DXBixh

Happy birthday to Pierre-Simon Laplace, the *actual* father of so called "Bayesian" Inference. en.wikipedia.org/wiki/Pierre-...

📣 Heads up! During 2025 #BiophysicsWeek the Membrane Structure and Function Subgroup is hosting a Webinar about “Milestones and Future Directions” in our field! It’s intended to be pedagogically accessible, and if you don’t mind me also presenting, then please consider signing up and logging in! 🧪🧬

FRIDAY - MARCH 14, 2025 Albert Einstein’s Birthday (1879) Also born on Pi-Day: Steph Curry, Simone Biles, and Billy Crystal

Theo Jansen's Strandbeests are massive, wind-powered kinetic sculptures designed to roam Dutch beaches. Conceived as a way to kick up sand that would replenish nearby dunes, the beests have grown into a decades-long obsession for the artist. fyfluiddynamics.com/?p=23401

The @ec-euclid.bsky.social mission to map part of the Universe has made a fascinating new discovery 💫 Our scientists are part of the team analysing the latest images from space 🔭 Read more 👉 tinyurl.com/bdze5xcy #DUresearch #DUinspire @esa.int #Einstein

Confinement, Jamming, and Adhesion in Cancer Cells Dissociating from a Collectively Invading Strand, W. Wang, R. A. Law, E. P. Ipiña, K. Konstantopoulos, and B. A. Camley, PRX Life 3 (2025) 🎉 go.aps.org/41xXR4N #Biophysics #Cancer #Jamming #CollectiveBehavior #Mechanobiology #SoftMatter #Metastasis

It was fun to uncover this story—bridging microbial physiology, biological pattern formation, & active matter physics. The results may even have implications for controlling microbes in applications. We'd love your feedback. Please report/share with whoever might be interested! [8/8]

Many biological fluids are polymer solutions, whose viscoelasticity can enhance cell swimming and promote large-scale mixing. We showed that the core-shell organization also arises in polymer solutions, but with fascinating additional flow fluctuations. [7/8]

We then developed a biophysical model describing this interplay quantitatively. The model recapitulates the experiments, and also yields criteria for predicting the different ways in which confined bacterial populations self-organize under different conditions. [6/8]

Cells consume O2, creating a gradient that alters motility: (i) They move up the gradient toward the droplet boundary via aerotaxis, & (ii) They stop swimming in the anoxic droplet core and accumulate. These motility variations in turn reshape O2 fluxes. A feedback loop! [5/8]

By simultaneously measuring cell distributions, oxygen concentration, and swimming-generated fluid flow, we figured out that this spatial organization is driven by the interplay between cell metabolism-generated oxygen gradients and collective motility. [4/8]

Surprisingly, when the droplets are big and concentrated, the cells self-organize into a concentrated inner "core" of immotile cells surrounded by a more dilute outer "shell" of highly motile cells. (See movie in 1st tweet.) In some cases, the core shrinks and disappears. [3/8]

Bacteria often inhabit confined spaces, such as biological tissues/gels & soils/sediments, where metabolites are scarce. What influence does confinement have on a population of motile bacteria? We addressed this question by studying quasi 2D droplets of swimming E. coli. [2/8]

Excited to release our latest work: doi.org/10.1101/2025... Here, we describe how confined bacterial suspensions self-organize into structured domains of different motilities, in response to oxygen limitations🦠🍥 Bluetorial follows! [1/8]

Science advances our economic, physical, and social and cultural wellbeing, and is key to a sustainable future. However, we live in times of great change, and the values that have driven science for the benefit of humanity are under threat. Read our statement here: royalsociety.org/news/2025/02...

To get an executive summary, have a look at our blog post: blogs.comphy-lab.org/Blog/2025-JF... and/or an `AI` generated general summary at bit.ly/4ifVrxg