Ripple bugs use a special fan-like structure on their middle legs to speed and steer through turbulent waters. In a new Science study, researchers report a water-walking robot inspired by this feature.
Want to know if inertia matters in your system? 🤓Compute the transition pressure pt and compare ΔP/pt: • If <1 → inertia negligible • If >1 → big efficiency loss Ex: 💧through a pore of square aspect ratio h/a=1 of radius… 1️⃣ 10 nm pore @30 bar → safe; 2️⃣ 10 µm pore @30 kPa → ~70% lost!
Using a simple U-tube, we measure pressure-driving flow through a single pore. At low Re, viscous drag dominates; but above Re ≈ 10, inertia takes over: resistance rises with pressure, overtaking viscosity. Simulations and model capture this transition from viscous to inertia regime 💻📝
Inertial correction to viscous drag along a pore length (Hagen-Poiseuille) are well studied; but this effect at the pore entrance (Sampson resistance) has received little attention, for example in work on end corrections for long pipes a century ago (Johansen Proc. R. Soc. A 1930)
Even if you reduce viscous drag with optimal geometry or special coatings, you still need to accelerate the fluid through the pore. That acceleration -- fluid inertia -- sets an upper bound on flow efficiency through micropores
Déployer ses ailes : la première étape cruciale de l’insecte adulte 🪰🦋🐞 Un article grand public avec @simonhadjaje.bsky.social et édité par Elsa Couderc
Fresh off the press, our work on wing deployment in Drosophila 🪰: www.nature.com/articles/s41... Work by: Simon Hadjaje, Ignacio Andrade-Silva, Marie-Julie Dalbe and Raphaël Clément
