An existence theory for solitary waves on a ferrofluid jet

Fuente: arXiv
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Autori principali: Groves, Mark D., Nilsson, Dag, Schütz, Leon
Natura: Preprint
Pubblicazione: 2025
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author Groves, Mark D.
Nilsson, Dag
Schütz, Leon
author_facet Groves, Mark D.
Nilsson, Dag
Schütz, Leon
contents We discuss axisymmetric solitary waves on the surface of an otherwise cylindrical ferrofluid jet surrounding a stationary metal rod. The ferrofluid, which is governed by a general (nonlinear) magnetisation law, is subject to an azimuthal magnetic field generated by an electric current flowing along the rod. We treat the governing equations using a modification of the Zakharov-Craig-Sulem formulation for water waves, reducing the problem to a single nonlocal equation for the free-surface elevation variable $η$. The nonlocality in the equation takes the form of a Dirichlet-Neumann operator whose analyticity (in standard function spaces) is demonstrated by studying its defining boundary-value problem in newly introduced Sobolev spaces for radial functions.\ Using rudimentary fixed-point arguments and Fourier analysis we rigorously reduce the equation for $η$ to a perturbation of a Korteweg-de Vries equation (for strong surface tension) or a nonlinear Schrödinger equation (for weak surface tension), both of which have nondegenerate explicit solitary-wave solutions. The existence theory is completed using an appropriate version of the implicit-function theorem.
format Preprint
id arxiv_https___arxiv_org_abs_2511_08799
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle An existence theory for solitary waves on a ferrofluid jet
Groves, Mark D.
Nilsson, Dag
Schütz, Leon
Analysis of PDEs
35Q35, 35Q53, 35Q55, 76B15
We discuss axisymmetric solitary waves on the surface of an otherwise cylindrical ferrofluid jet surrounding a stationary metal rod. The ferrofluid, which is governed by a general (nonlinear) magnetisation law, is subject to an azimuthal magnetic field generated by an electric current flowing along the rod. We treat the governing equations using a modification of the Zakharov-Craig-Sulem formulation for water waves, reducing the problem to a single nonlocal equation for the free-surface elevation variable $η$. The nonlocality in the equation takes the form of a Dirichlet-Neumann operator whose analyticity (in standard function spaces) is demonstrated by studying its defining boundary-value problem in newly introduced Sobolev spaces for radial functions.\ Using rudimentary fixed-point arguments and Fourier analysis we rigorously reduce the equation for $η$ to a perturbation of a Korteweg-de Vries equation (for strong surface tension) or a nonlinear Schrödinger equation (for weak surface tension), both of which have nondegenerate explicit solitary-wave solutions. The existence theory is completed using an appropriate version of the implicit-function theorem.
title An existence theory for solitary waves on a ferrofluid jet
topic Analysis of PDEs
35Q35, 35Q53, 35Q55, 76B15
url https://arxiv.org/abs/2511.08799