Exact dispersion relation for linear surface waves on arbitrary vertical shear

Fuente: arXiv
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Main Authors: Heinrich, Kjell S., Ellingsen, Simen Å.
Format: Preprint
Published: 2026
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author Heinrich, Kjell S.
Ellingsen, Simen Å.
author_facet Heinrich, Kjell S.
Ellingsen, Simen Å.
contents We derive the formal solution to the dispersion relation for linear surface waves on a horizontal mean current with arbitrary vertical dependence. The problem is cast in a Green's function framework for the Rayleigh equation, neglecting viscosity but making no further approximations about the mean velocity profile. The solution is the dispersion relation in the form of a single, implicit equation relating -- and containing only -- the velocity profile, wave frequency, and wavenumber. By isolating curvature effects in a path-ordered exponential, we obtain a solution that serves as a natural starting point for systematic approximations. We demonstrate that our solution reduces to the expression found by Shrira (1993, J. Fluid Mech. 252, 565--584) in the deep-water limit, yields known asymptotic approximations, and recovers known analytical solutions in special cases.
format Preprint
id arxiv_https___arxiv_org_abs_2604_24484
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Exact dispersion relation for linear surface waves on arbitrary vertical shear
Heinrich, Kjell S.
Ellingsen, Simen Å.
Fluid Dynamics
We derive the formal solution to the dispersion relation for linear surface waves on a horizontal mean current with arbitrary vertical dependence. The problem is cast in a Green's function framework for the Rayleigh equation, neglecting viscosity but making no further approximations about the mean velocity profile. The solution is the dispersion relation in the form of a single, implicit equation relating -- and containing only -- the velocity profile, wave frequency, and wavenumber. By isolating curvature effects in a path-ordered exponential, we obtain a solution that serves as a natural starting point for systematic approximations. We demonstrate that our solution reduces to the expression found by Shrira (1993, J. Fluid Mech. 252, 565--584) in the deep-water limit, yields known asymptotic approximations, and recovers known analytical solutions in special cases.
title Exact dispersion relation for linear surface waves on arbitrary vertical shear
topic Fluid Dynamics
url https://arxiv.org/abs/2604.24484