Simulates the Saint-Venant (shallow water) equations: ∂h/∂t + ∂(hu)/∂t = 0, ∂(hu)/∂t + ∂(hu²+gh²/2)/∂x = 0. Steepening leads to wave breaking via shock formation.
Froude: Fr = u/√(gh) · Wave speed: c = √(gh) · Steepening: ∂u/∂x < 0 → shock