Ripple Tank: 2D Wave Equation & Interference

Interaction mode

Click or drag on the tank to drop disturbances into the water.

Wave field

Wave speed 0.16

Damping 0.006

Pulse strength 1.2

New sources

Source frequency 1.0 Hz

Source amplitude 0.8

Tank state

Sim time

0.0 s

Energy

0.0

Active sources

FPS

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How it works

Every cell of a 180×120 grid stores a water-surface height h. Each step solves the discretized 2D wave equation with a five-point Laplacian:

h'(x,y) = h(x,y) + [h(x,y) − h_prev(x,y)]·(1 − damping) + c²·(h_left + h_right + h_up + h_down − 4·h(x,y))

Wave speed (c²) — how fast a disturbance's energy spreads to neighbouring cells each step; higher values propagate ripples faster and let waves travel further before decaying.
Damping — bleeds off velocity every step, so ripples fade instead of ringing forever, the way real capillary/gravity waves lose energy to viscosity.
Reflection — the tank edges are held fixed at zero height (a Dirichlet boundary), so any wave reaching a wall reflects back into the tank with inverted phase, exactly like a wave on a string tied to a fixed post.
Interference — because the wave equation is linear, heights from multiple sources simply add. Two continuous point sources oscillating in phase produce the classic bright/dark interference fringes where crests reinforce or crests meet troughs and cancel.