Water Wave Propagation: 2D Ripple Tank (FDTD)

Wave Medium

Wave speed (c) 2.20 m/s

Damping 0.006

Sources

Drop amplitude 0.9

Live Readout

Elapsed time

0.0 s

Max amplitude

0.000

Surface energy

0.00

Drops so far

How it works

This is a real finite-difference (FDTD) solution of the 2D scalar wave equation on a grid, not a shader approximation:

∂²u/∂t² = c²·∇²u − 2γ·∂u/∂t

u[i,j]ⁿ⁺¹ = 2u[i,j]ⁿ − u[i,j]ⁿ⁻¹
  + (cΔt/Δx)²·(u[i+1,j]+u[i−1,j]+u[i,j+1]+u[i,j−1]−4u[i,j])ⁿ
  − 2γΔt·(u[i,j]ⁿ − u[i,j]ⁿ⁻¹)

Every grid cell only ever talks to its four direct neighbours each step — that local update rule is what makes circular wavefronts, interference fringes and reflections emerge on their own, with no ray-tracing or hand-authored ring formula involved.

Rain — random point sources land at intervals, the classic "raindrops on a pond" pattern.
2-Source — two fixed emitters oscillate continuously, producing a textbook standing interference pattern of bright/dark fringes.
Manual — click or tap anywhere on the tank to drop a pulse exactly where you point.
Boundary — Reflective clamps the edge cells (walls bounce waves back); Absorbing fades the last few rows so waves leave the tank instead of reflecting.
Surface energy — Σu² over the grid, a proxy for total wave energy; damping bleeds it away over time, matching real dissipation.

Click / tap the water to drop a pulse