Rigorous derivation of the Whitham equations from the water waves equations in the shallow water regime

Abstract

We derive the Whitham equations from the water waves equations in the shallow water regime using two different methods, thus obtaining a direct and rigorous link between these two models. The first one is based on the construction of approximate Riemann invariants for a Whitham-Boussinesq system and is adapted to unidirectional waves. The second one is based on a generalisation of Birkhoff's normal form algorithm for almost smooth Hamiltonians and is adapted to bidirectional propagation. In both cases we clarify the improved accuracy on the fully dispersive Whitham model with respect to the long wave Korteweg-de Vries approximation.

References in corpus (5)

• The Whitham Equation as a Model for Surface Water Waves
• On Whitham's conjecture of a highest cusped wave for a nonlocal dispersive equation
• The wave breaking for Whitham-type equations revisited
• Global bifurcation of solitary waves for the Whitham equation
• Enhanced existence time of solutions to evolution equations of Whitham type