Same flow field structure as Flow Field #2, but the direction at each step is driven by layered noise instead of a single octave:

fBm = noise(x,y) + 0.5·noise(2x,2y) + 0.25·noise(4x,4y) + …

Each octave doubles the frequency and halves the amplitude, adding finer detail on top of the large-scale structure. The result feels more atmospheric than single-octave noise — like wind or water turbulence at multiple scales simultaneously.

Key variables: octaves (2 = close to plain flow field, 6 = rich fractal turbulence), gain (how fast amplitude shrinks per octave), lacunarity (how fast frequency grows per octave).