🌀 FlowLab

Real-time 2D incompressible flow — 100% GPU via WebGPU compute, in your browser.

Run it

uv run uvicorn server:app --reload --port 8000

Open http://localhost:8000 in Chrome (WebGPU required).

Using FlowLab

• Kármán Vortex (default) — cylinder in a wind tunnel, vortex street live.
• Backward Step — no obstacle until you click the canvas to insert one.
• First visit opens a 12-step onboarding tour; replay it anytime via Replay the Tour in the guide.
• The ? button opens the in-app guide — the full user manual.

Key	Action
P	Play / pause
M	Step one frame
1-2	Load preset

Drag the obstacle through the flow; Shift+mousemove rotates it. Sliders set Re, inflow velocity, and iterations; resolution switches in discrete tiers (64–1024).

Understanding & hacking FlowLab

• docs/architecture.md — system + module map
• docs/gpu-pipeline.md — WGSL pipelines, buffers, bind groups
• docs/numerical-methods.md — solver math + measured numbers
• docs/adr/README.md — 11 design decisions
• docs/ROADMAP.md — where it's going
• CONTEXT.md — project vocabulary
• docs/README.md — full annotated index

Numbers

Measured, not asserted — derivations in docs/numerical-methods.md:

• Honest Reynolds window Re 4.1 … 154 (startup tier 256²; every tier re-measured)
• Vortex-shedding onset Re 52.2
• Strouhal St 0.166 … 0.200, recovered live from the wake
• 526 GPU dispatches/frame at 256² (256 pressure iterations, default Re, incl. gauge normalization)
• Resolution tiers 64–1024 (1024 manual-only)

Develop

• npx playwright test — 104/104 Playwright; headed, port 8321, --enable-unsafe-webgpu (all config defaults)
• No build step — vanilla ES modules
• Dockerfile for deploy