Flow past an obstacle, from smooth laminar streamlines to a Kármán vortex street to a turbulent wake — solved in real time on the GPU.
Built with SceneryStack, Vite 8, TypeScript 7 and Biome 2.
Dye is injected in bands at the left edge of a channel and carried past a body in the middle. Raising the flow speed (or lowering the viscosity) raises the Reynolds number, and the wake changes character: attached and symmetric below Re ≈ 47, shedding a periodic train of alternating vortices above it, and losing coherence entirely by Re ≈ 200. The Reynolds number and the regime it implies are shown beneath the field.
- Intro — a fixed cylinder and one control: flow speed.
- Lab — viscosity, obstacle size, shape (cylinder, flat plate, airfoil) and position, and four views of the field (dye, speed, vorticity, pressure). Vortex detail, dye fade and grid resolution live in Preferences → Simulation. Drag anywhere in the channel to push the fluid and add dye.
WebGPU required. The solver is Jos Stam's Stable Fluids running entirely in WGSL compute shaders — there is no CPU fallback. Recent Chrome, Edge and Safari support it. Where it is unavailable the sim boots normally and shows a message in place of the field.
See doc/model.md for the physics and its limits, and
doc/implementation-notes.md for the architecture.
- Stable Fluids solver in WGSL compute shaders (MacCormack advection, implicit viscous diffusion, vorticity confinement, red-black SOR pressure projection)
- Analytic signed-distance obstacles, so the body can be dragged and resized with no GPU resource churn
- Live accessible description of the flow, shared by the field and the screen summaries
- English, Spanish, and French localization via
StringManager - Default and projector color profiles
- Progressive Web App (installable, offline-capable)
- Git hooks for Biome pre-commit checks
- Shared GitHub Actions CI via
OpenPhysics/Baton
npm install
npm run icons # generate PNG icons from public/icons/icon.svg
npm start # dev server → http://localhost:5173| Command | Description |
|---|---|
npm start / npm run dev |
Start Vite dev server |
npm run build |
Type-check + production build → dist/ |
npm run preview |
Preview the production build locally |
npm test |
Run Vitest unit tests (includes memory-leak suite) |
npm run test:fuzz |
Playwright: the WebGPU engine integration test + ?fuzz smoke |
npm run test:fuzz:quick |
Shorter fuzz smoke (10s) |
npm run check |
TypeScript type check |
npm run lint |
Biome lint check |
npm run format |
Auto-format all files |
npm run fix |
Lint + auto-fix |
npm run icons |
Regenerate PNG icons from public/icons/icon.svg |
npm run clean |
Remove dist/ |
| Tool | Version | Purpose |
|---|---|---|
| SceneryStack | ^3.0.0 | Simulation framework |
| Vite | ^8 | Build tool + dev server |
| TypeScript | ^7 | Type-safe JavaScript |
| Biome | ^2.5 | Linting + formatting |
| vite-plugin-pwa | ^1 | PWA + service worker |
GNU Affero General Public License v3.0 — see OpenPhysics org license.
See OpenPhysics contributing guidelines. Report bugs via GitHub Issues; use org issue templates.