Flow loop — streaklets · a bubble grows in the stream · the handedness flips

One seamless 12-second loop, three beats: particles rendered as velocity streaklets (line segments along the local flow, not dots); a glassy bubble grows mid-stream and the flow parts around it — a fresnel rim over an exactly divergence-free boundary built from the emitted vector potential (u = ramp·u + ramp′·n×A, radius is just a uniform); then the field's helicity morphs −0.9 → +0.9 by mixing two emitted fields in-shader (a mix of divergence-free fields is divergence-free), so the whole stream reverses its swirl — amber left-handed ↔ teal right-handed. Camera makes one full orbit per loop, so the loop closes. Drag to orbit, scroll to zoom.