LightNews — News, ranked by scholars

Ted Underwood

@tedunderwood.com

so sick of AI / fluid dynamics discourse on this app; now to relax with a big swig of hot milky tea

$GPT-5.6: This is actually a lovely everyday visualization of Navier–Stokes. The coffee and cream are fluids with a velocity field \mathbf u(\mathbf x,t): at every point in the cup, the liquid has some direction and speed. Navier–Stokes describes how that field evolves, \rho\left(\frac{\partial \mathbf u}{\partial t}+\mathbf u\cdot\nabla\mathbf u\right) = -\nabla p+\mu\nabla^2\mathbf u+\mathbf f. In the photograph you can almost assign each term a visible role: * \mathbf u\cdot\nabla\mathbf u: advection/inertia. The curling cream filaments reveal parcels of liquid being swept around by the existing circulation. Their folds and tendrils are basically tracers of the hidden velocity field. * -\nabla p: pressure forces. Pressure gradients help establish and redirect the circulating flow, especially after pouring or stirring. * \mu\nabla^2\mathbf u: viscosity. This damps sharp differences in velocity. The whorls don’t keep getting faster and finer forever; their kinetic energy dissipates and the coffee eventually becomes still. * \mathbf f: body forces, especially gravity/buoyancy. If the cream and coffee differ in density or temperature, buoyancy can generate some of the rising and sinking plumes. There is one nice wrinkle: Navier–Stokes itself does not directly describe the changing cream color. The cream concentration c is approximately a passive scalar obeying an advection–diffusion equation \frac{\partial c}{\partial t}+\mathbf u\cdot\nabla c = D\nabla^2 c. So the spectacular visible swirls are the cream making the invisible Navier–Stokes velocity field visible. Advection stretches the cream into long thin sheets; molecular diffusion then mixes efficiently across those increasingly narrow sheets. The picture therefore captures a central fluid-dynamical idea very well: flow creates structure at large scales, stretching and folding pushes it toward smaller scales, and viscosity/diffusion ultimately erase it.$ $This is actually a lovely everyday visualization of Navier–Stokes. The coffee and cream are fluids with a velocity field \mathbf u(\mathbf x,t): at every point in the cup, the liquid has some direction and speed. Navier–Stokes describes how that field evolves, \rho\left(\frac{\partial \mathbf u}{\partial t}+\mathbf u\cdot\nabla\mathbf u\right) = -\nabla p+\mu\nabla^2\mathbf u+\mathbf f. In the photograph you can almost assign each term a visible role: * \mathbf u\cdot\nabla\mathbf u: advection/inertia. The curling cream filaments reveal parcels of liquid being swept around by the existing circulation. Their folds and tendrils are basically tracers of the hidden velocity field. * -\nabla p: pressure forces. Pressure gradients help establish and redirect the circulating flow, especially after pouring or stirring. * \mu\nabla^2\mathbf u: viscosity. This damps sharp differences in velocity. The whorls don’t keep getting faster and finer forever; their kinetic energy dissipates and the coffee eventually becomes still. * \mathbf f: body forces, especially gravity/buoyancy. If the cream and coffee differ in density or temperature, buoyancy can generate some of the rising and sinking plumes. There is one nice wrinkle: Navier–Stokes itself does not directly describe the changing cream color. The cream concentration c is approximately a passive scalar obeying an advection–diffusion equation \frac{\partial c}{\partial t}+\mathbf u\cdot\nabla c = D\nabla^2 c. So the spectacular visible swirls are the cream making the invisible Navier–Stokes velocity field visible. Advection stretches the cream into long thin sheets; molecular diffusion then mixes efficiently across those increasingly narrow sheets. The picture therefore captures a central fluid-dynamical idea very well: flow creates structure at large scales, stretching and folding pushes it toward smaller scales, and viscosity/diffusion ultimately erase it.$

September 8, 2026 at 5:25 PM

Froyok (Léna Piquet)

@froyok.fr

"FFT Bloom Optimized to the Bone in Nabla" by Francisco Letterio on the GP blog.
graphics-programming.org/blog/fft-blo...

#rendering #graphics-programming #bloom

FFT Bloom Optimized to the Bone in Nabla | Graphics Programming Discord

Understanding and using the Nabla FFT

graphics-programming.org

January 24, 2025 at 10:54 PM

Guillaume

@guipascanet.bsky.social

Nabla Leviste: J'adore ce mec! Génial!

ALT: Nabla Leviste: J'adore ce mec! Génial!

static.klipy.com

September 25, 2026 at 4:44 PM

DaUTF/Uli 🔜 BITE9 & Midsummer Melody

@dautf.bsky.social

SOUND VOLTEX ∇(NABLA)

November 15, 2025 at 2:31 AM

celebi

@syrebi.bsky.social

November 15, 2025 at 12:54 AM

nightshade →home, for now

@nightshade.technology

"nabla" lmao

November 15, 2025 at 1:05 AM

Purrcelain 💜✨🐾 Kintsugi Cat Vtuber

@purrcelaindoll.bsky.social

Finally got out to the arcade and got some time in on the new Voltex, got arcade VF class up to 4!

A screenshot of Sound Voltex Nabla showing a class promotion to Cyan

A Sound Voltex Nabla result screen showing a UC AAA+ on Necromantic

A Sound Voltex Nabla result screen showing a AAA on Retry Now

A Sound Voltex Nabla result screen showing a AAA on Science

January 12, 2026 at 12:46 AM

Phia Phia Phia!! 🐁☀️

@mousephia.love

This is an Xbox.

Sound Voltex Valkyrie Model cabinet running NABLA, notably with green lights. basically an xbox right

December 24, 2025 at 10:59 AM

zxettai.bsky.social

@zxettai.bsky.social

Rasis from SDVX Nabla! #sdvx #sdvx_art #sketch

November 18, 2025 at 7:06 AM

shadecho

@shadecho.bsky.social

Unity
#asoe #oc #art

Lineup of monochromatic characters
From left to right: Kat, JAI, Nim, Don, Laz, Cerise, and Nabla.

May 12, 2025 at 7:22 PM

Diego del Alamo

@delalamo.xyz

A technical paper on de novo designed antibodies nabla-public.s3.us-east-1.amazonaws.com/2024_Nabla_J...

nabla-public.s3.us-east-1.amazonaws.com

November 23, 2024 at 7:59 AM

ᴳʳⁱˡˡᵉᴿ █▒░𝕯𝖗𝖊𝖆𝕸𝖘░▒█

@mewdles.com

downward thoughts
#mewdsart #sfw #personal #icon #mewds
2026 Aug 23

Blue Mewds in the void while downward pointing triangles (otherwise known as "nabla") effervescing from his head.

August 23, 2026 at 9:58 PM

shadecho

@shadecho.bsky.social

supernova
#oc #asoe #art

prism (bottom right) and nabla (top left) reaching out to each other

December 19, 2024 at 4:55 AM

Trouble System

@treat.kandicritter.sqky.one

the diapersexual flag went so well let's make a median plural flag too what's the worst that could happen

a black nabla (upsdiedown triangle with a thicker left line) on a white background with four stripes coulourpicked from emmengard's rings in the middle going underneath the nabla.

March 19, 2024 at 5:17 AM

トリギヤ/illustration🐦🦉

@torigiya296.bsky.social

#Nabla小隊
同時進行メイキング

January 16, 2026 at 1:23 PM

Nabla

@nablastria.bsky.social

Ugh Procreate: 1; Nabla: 0 here

#badeni #orb #チ

April 9, 2026 at 12:05 AM

トリギヤ/illustration🐦🦉

@torigiya296.bsky.social

過去に作ってた創作っ子リメイクしました

#Nabla小隊 #鳥木屋展

January 12, 2026 at 3:10 PM

Florian Aigner

@florianaigner.at

Natürlich ist Kälte die Abwesenheit von Wärme. Das heißt aber nicht, dass sich nicht Kälte genauso "ausbreiten" kann wie Wärme. Es gibt mathematisch keinen Unterschied. Das hier ist die Wärmeleitungsgleichung:

Die Wärmeleitungsgleichung: dT nach dt - also die zeitliche Ableitung der Temperatur - ist proportional (mit Proportionalitätsfaktor alpha) zur zweiten Ortsableitung (dreidimensional: Nabla zum Quadrat) der Temperatur.

December 20, 2025 at 1:04 PM

matjaz6

@njetwork.si

Moj stari bend Nabla X je razpadel v dreku zamer, ampak tale komad je še vedno ok in, žal, še vedno aktualen:
nablax.bandcamp.com/track/odhajam

Odhajam!, by Nabla X

from the album Julija in sedem palčkov

nablax.bandcamp.com

August 21, 2026 at 5:48 PM

Viccionari

@viccionari.bsky.social

«nabla»

Etimologia: Del llatí 'nabla', del grec antic 'νάβλα'.

na·bla, nom masculí (plural «nables»)

1. (música) Instrument musical hebreu de deu cordes amb un marc rectangular.

(1/2)

Dibuix esquemàtic d’un nabla.

Aaron Walden (Wikimedia Commons, CC BY-SA 3.0)

June 27, 2025 at 10:53 AM

STAT

@statnews.com

Artificial intelligence developer Nabla has raised $70 million as the company looks to expand its software that automates clinical note-taking to additional applications, like billing. www.statnews.com/2025/06/17/n...