The Cubic Vortical Whitham Equation

Autor: John D. Carter, Henrik Kalisch, Christian Kharif, Malek Abid
Přispěvatelé: Institut de Recherche sur les Phénomènes Hors Equilibre (IRPHE), Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS)
Rok vydání: 2021
Předmět:
Zdroj: Wave Motion
Wave Motion, 2022, 110, pp.102883. ⟨10.1016/j.wavemoti.2022.102883⟩
ISSN: 0165-2125
1878-433X
DOI: 10.48550/arxiv.2110.02072
Popis: The cubic-vortical Whitham equation is a model for wave motion on a vertically sheared current of constant vorticity in a shallow inviscid fluid. It generalizes the classical Whitham equation by allowing constant vorticity and by adding a cubic nonlinear term. The inclusion of this extra nonlinear term allows the equation to admit periodic, traveling-wave solutions with larger amplitude than the Whitham equation. Increasing vorticity leads to solutions with larger amplitude as well. The stability of these solutions is examined numerically. All moderate- and large-amplitude solutions, regardless of wavelength, are found to be unstable. A formula for a stability cutoff as a function of vorticity and wavelength for small-amplitude solutions is presented. In the case with zero vorticity, small-amplitude solutions are unstable with respect to the modulational instability if kh > 1.252, where k is the wavenumber and h is the mean fluid depth.
Databáze: OpenAIRE