What pattern do the ripples make once they bounce off the edges and cross the outgoing ones? Rings spread from the center about 6 to 7 patches apart and reach the edges after roughly 250 ticks. They look slightly square, an artifact of the four-neighbor grid at this wavelength.
Try this Set damping from 0.5 to 0 while it runs (it takes effect live). Reflections stop fading, interference fills the board, and wave-energy keeps climbing, by about 1 per tick, instead of leveling off.
About this model Where it ends up
A discretized two-dimensional wave equation, after Uri Wilensky's NetLogo Wave Machine. Each patch accelerates toward the average height of its four neighbors, so a disturbance travels outward as a ring, and a sine-driven center patch keeps sending rings that reflect off the edges and interfere.
Each patch stores a height and a velocity, and all patches update together each tick. The center patch is set to drive-amplitude × sin(2π × tick / drive-period). Every other patch adds stiffness × (neighbor average − height) to its velocity, loses damping percent of it, and adds the result to its height. At the edges a missing neighbor counts as the patch's own height, so the edges are free and reflect waves without flipping them. Waves travel at about √stiffness / 2 patches per tick (0.27 at the default), and all four params are read every tick.
wave-energy sums velocity squared, so it counts kinetic energy only. crest-height and trough-height include the driven patch, so they mostly show its swing rather than the ripples.
