Live model of the sealed toroidal ferrofluid ratchet: 3.5″ torus, raceway of EFH1 + one N52 slug (axial magnetization, long axis tangential), single continuous conductor sewn in the {12/5} star (1→6→11→4→9→2→7→12→5→10→3→8), driven differentially — stereo L (314 Hz) one end, R (3140 Hz) the other, coil current = L − R.
COMPUTED (Maxwell-exact): the magnetic field lines. Traced live through the total field — winding filaments (Biot–Savart) + the dominant axial dipole of the 5-loop bore component + the live rotating N52 slug — seeded across radii so they show the true nested topology: down through the bore, ballooning out past the shell, curving back through the bore, standing off the shell at every angle. This is real determined physics; get the sources right and this shape is forced.
MODELED (calibrated, not first-principles): the ferrofluid response and the lap-rate. The fluid enters as slug drag + a calibrated entrainment carrying the bench anchor (vol 2 ≈ 1 lap/s = 26ᵗʰ subharmonic of the 26.17 laps/s capture speed). Full nonlinear ferrohydrodynamics is NOT computed in-browser — no tabletop sim does that. The swirling FIELD is physics; any fluid motion shown is a labeled model.
The winding's five net encirclements of the vertical axis make a current loop around the bore — its field is an axial dipole, poles at top and bottom of the hole. That is exactly the through-hole-and-around-outside pattern. The slug adds a rotating perturbation that sweeps the structure once per lap; slow the time scale to watch it turn.
Copper glows with |I(t)|. Cyan/orange field lines thread the bore and wrap the tube, retracing continuously. Slug's white stripe = billet spin. Grey bar in the eye = ferrous follower (tachometer), co-rotating. Drag to orbit, pinch/wheel to zoom, slow the time scale to watch the wave.