Kaare H. Jensen

@johnseb.bsky.social

Our new paper is now out in PNAS: "The geometry of Nature’s stingers is universal due to stochastic mechanical wear." doi.org/10.1073/pnas... . Original artwork by John Sebastian

This week, I tried to recreate the cover image of Benny Lautrup’s Physics of Continuous Matter, using nothing more exotic than syrup and glitter. #FluidsFriday

We’ve been putting together a small device to study flow through pores, where geometry matters and minor imperfections can make or break the experiment. The goal is simple to state and nontrivial to execute. One early prototype looks, quite unintentionally, like a Picasso: a face, a pair of eyes.

Reflections #FluidsFriday

Take a break from the tyranny of familiarity! Experiments reveal that magnets, normally expected to snap onto ferromagnetic surfaces (fridge doors) instantly, cannot overcome hydrodynamic forces to achieve finite-time contact in viscous fluids. Now out in JFM: doi.org/10.1017/jfm.... #FluidsFriday

William Pickard developed an elegant analytical solution to describe low-Reynolds-number flow in long cylindrical cells. This setup resembles the classic Couette flow, but in this case, the velocity depends on the angle and the radial position (normalized by the cell radius) buff.ly/RcuIAyW

It's #FluidsFriday, and we're featuring another sample from the hydrodramatic toy collection. A rising Taylor bubble generates a swirling flow inside a sealed cylindrical tube.

Roses don’t just defend themselves. Their prickles are geometrically ideal for gripping surfaces, supporting vertical growth, and, when needed, creating lacerations that deter herbivores. Students - join us to investigate how biological form and physical law work together!

So much of our daily lives involves fluids moving from one place to another. It's great when it works. But sometimes it fails. A leak appears. A drop gets through. And then another.

🌿Join us for the Webinar Series 2025 – Road to The 11th International Plant Biomechanics Conference 2026 🌍
📅 Webinar #1: Sept 25, 2025 | [Register: ugm.id/PBMweb1]
📅Webinar #2: Oct 9, 2025 | [Register: ugm.id/PBMweb2]

🚰 Fluid inertia limits microporous flow efficiency, out in EPJ Plus this week, with Kaare Jensen @jensen-research.bsky.social‬ rdcu.be/eBV2C 👇

We have two open Post-Doc positions in my group at the interface with:
1- @ataly.bsky.social for molecular dynamics
2- Bruno Guillotin from protein mobility

Apply by sending CV, two ref letters and a short motivation letter to me : emmanuelle.bayer@u-bordeaux.fr. Deadline 15 sept.

The Gallery of Soft Matter 2025 @apsdsoft.bsky.social has some amazing entries this year. Check them out here: engage.aps.org/dsoft/galler....
Make sure to vote! Not sure about the deadline, but there’s a QR code at the DSOFT table with all the details.

Thanks for reminding me about the four domains I have at Hover (including papermachete.org)

Defying gravity: insights into hula hoop levitation – Physics World Successful hula hooping requires a gyrating body with a particular slope and curvature

I've always been bad at hula-hooping, but I never knew why until I read this article. Turns out it's *not* a lack of coordination or weak core muscles, it's my body type! ⚛️🧪
physicsworld.com/a/defying-gr...

The 10 quirkiest stories from the world of physics in 2024 – Physics World We revisit the physics of papercuts, a quantum escape room and much more

Finally, we firmly believe there is physics everywhere you look, including in paper cuts, escape rooms, stamps, cicadas and a whole bunch of other unlikely places. Here's @michaelbanks.bsky.social's take on 2024's quirkiest physics stories. Happy new year! (8/end) 🧪⚛️ physicsworld.com/a/the-10-qui...