Sand settles on the nodal lines
This top-down companion renders the same Chladni-figure mathematics as the 3D plate simulation, viewed flat from above. A vibrating square plate driven at a chosen mode (n, m) and frequency has a standing-wave displacement field with fixed nodal lines where the surface barely moves; thousands of sand grains drift down the local vibration gradient and jitter proportionally to nearby amplitude, so over a few seconds they collect into the classic Chladni figure along those nodes. Mode numbers, drive frequency, vibration energy and settling speed all carry over as live controls, matching the 3D scene's parameter set.