Top-down view of the same standing-wave physics as the 3D version: a square plate vibrates at a
driven frequency, and sand grains migrate away from antinodes (high-amplitude regions) toward
nodal lines (zero-amplitude), tracing the plate's vibration eigenmode as a 2D pattern.
Characteristics
- Particles: up to 6000, adjustable live
- Field: f(x,y) = sin(nπx/L)sin(mπy/L) − sin(mπx/L)sin(nπy/L)
- Particles descend the gradient of |f|, so they settle on its zero-crossings
- Mode numbers (n,m) step through 21 discrete pairs as frequency rises