Shorebreak

surf physics, live

What's being simulated

Wind sea. A JONSWAP spectrum with Hasselmann directional spreading, synthesised by GPU inverse FFT over three cascades (256 m, 47 m, 9 m), with choppy horizontal displacement. Whitecaps appear where the Jacobian of that displacement folds.
Swell. Five components march in from 10 m depth. Each follows linear dispersion ω² = gk tanh kh. Snell's law refracts the crests shore-parallel, and energy-flux conservation shoals them.
Breaking. Thornton–Guza random-wave dissipation drains energy over the crescentic bar and inner terrace. Individual crests saturate at 0.78× the depth and pitch forward as they break. Rip channels let sets through unbroken.
Wave shape. The Ursell number sets skewness and asymmetry (Ruessink 2012), which feed the Abreu 2010 waveform. Crests turn peaky and fronts steepen into bores.
Setup & currents. Radiation-stress gradients raise the mean shoreline. A cell circulation feeds narrow rip jets through the channels, and they carry foam out to sea.
Swash. A 2D shallow-water solver (virtual pipes, bed friction, wetting/drying) on the foreshore. It is driven by the incoming bores, so water runs up, stalls and drains back. The sand stays dark where it was wetted and glistens while the film drains.
Light. Rayleigh + Mie single-scattering sky, a lit cloud layer that casts shadows, Fresnel reflection and a GGX sun glint. Beer–Lambert absorption and backscatter tint the water column. Bubbles brighten broken water, crests glow when backlit, and caustics move on the seabed.

Drag to look · right-drag or two fingers to move · scroll to zoom