Tracing the flow…
NAVIER–STOKES / A VISUAL STUDY
The shape
of a singularity.
A fluid spirals inward, spins faster,
and stretches along its axis.
Follow the motion into the core.
ANGULAR ROTATION
SlowerFaster
MOTION BALANCE · ACTUAL EQUATION
∂tu + (u · ∇)u − νΔu + ∇p = f
Acceleration, transport, viscosity and pressure balance a smooth force.
INCOMPRESSIBILITY + CORE SHAPE
∇ · u = 0 · ℓr ≍ τ1/2 ℓz ≍ τ1/2−h
Radial inflow is balanced by axial outflow; the core becomes slender.
WHY SMOOTHNESS BREAKS · τ = 1 − t → 0
|uθ|, |uz| ≍ τ−1/2−h → ∞
Peak velocity diverges at t = 1 while shrinking volume keeps energy finite.
Inward spiral
Axial stretching
Faster core