Hodge Decomposition

Every vector field = gradient (curl-free) + curl (div-free) + harmonic

Original F
Curl-free ∇φ
Div-free ∇×A
Harmonic H
Hodge theorem:
F = ∇φ + ∇×A + H

∇φ — curl-free (irrotational)
grad of scalar potential

∇×A — div-free (solenoidal)
curl of vector potential

H — harmonic component
both curl-free and div-free

Computed via spectral method (DFT on grid).