Swirl ill-posedness for incompressible fluids in (sub)critical spaces
Abstract
For the 3D Navier-Stokes equations with sufficiently smooth initial data having zero swirl u0θ≡ 0, Ladyzhenskaya \cite{L1968} and Ukhovskii and Yudovich \cite{UY1968} established global regularity. It has since remained open as to whether well-posedness still holds for smooth axisymmetric initial data, with the initial swirl being smaller than an \textit{absolute} constant in a critical space. In this remark, we prove \textit{norm inflation} occurs for the Navier-Stokes scalar swirl component, with initial smallness in the critical space Ḣ1/2 or even subcritical Sobolev spaces. We also obtain norm inflation for the 3D Euler swirl \textit{vector} in the Euler subcritical space Ḣ3. Our results are achieved by introducing an anisotropic scale in Luo's supercritical norm inflation construction \cite{Luo24}, as well as performing an anisotropic bootstrap argument to get a sufficiently small swirl remainder term.
Related
- Illposedness of incompressible fluids in supercritical Sobolev spaces
- Asymptotic profiles for solutions to the incompressible Navier-Stokes equations in the critical Fourier-Herz spaces
- Global well-posedness and scattering of energy-critical defocusing nonlinear Schrödinger equation on high-dimensional hyperbolic spaces
- Local well-posedness of the two-dimensional Incompressible Schrödinger flow
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BibTeX
@misc{barker2026swirl,
title = {{Swirl ill-posedness for incompressible fluids in (sub)critical spaces}},
author = {Tobias Barker and Ruilin Hu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.33973},
eprint = {2610.33973},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.33973},
}
RIS
TY - UNPB
TI - Swirl ill-posedness for incompressible fluids in (sub)critical spaces
AU - Tobias Barker
AU - Ruilin Hu
PY - 2026
DA - 2026/10/25
PB - arXiv
DO - 10.48550/arxiv.2610.33973
UR - https://arxiv.org/abs/2610.33973
AB - For the 3D Navier-Stokes equations with sufficiently smooth initial data having zero swirl u_0θ≡ 0, Ladyzhenskaya \cite{L1968} and Ukhovskii and Yudovich \cite{UY1968} established global regularity. It has since remained open as to whether well-posedness still holds for smooth axisymmetric initial data, with the initial swirl being smaller than an \textit{absolute} constant in a critical space. In this remark, we prove \textit{norm inflation} occurs for the Navier-Stokes scalar swirl component, with initial smallness in the critical space Ḣ^1/2 or even subcritical Sobolev spaces. We also obtain norm inflation for the 3D Euler swirl \textit{vector} in the Euler subcritical space Ḣ^3. Our results are achieved by introducing an anisotropic scale in Luo's supercritical norm inflation construction \cite{Luo24}, as well as performing an anisotropic bootstrap argument to get a sufficiently small swirl remainder term.
ER -