PreprintarXiv licencearXiv
Long-time stability of hierarchical point vortex configurations
Abstract
In this paper, we investigate the dynamics and long-time stability of hierarchical configurations in an N-point vortex system on ℝ2 and in simply connected domains, without the Cantor-set restriction inherent in KAM theory. Since the Hamiltonian perturbation lacks a standard power-series expansion in the usual normalized variables, we develop a modified Birkhoff normal form based on successive ratios of adjacent variables, tailored to the hierarchical structure. A key feature is the preservation of the resulting natural exponent structure throughout the normal form procedure. Consequently, for n sufficiently large, the hierarchical configuration persists for times of order at least ε−(n−2(N−1)).
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BibTeX
@misc{ibrahim2026longtime,
title = {{Long-time stability of hierarchical point vortex configurations}},
author = {Slim Ibrahim and Shengyi Shen},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.23719},
eprint = {2609.23719},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.23719},
}
RIS
TY - UNPB
TI - Long-time stability of hierarchical point vortex configurations
AU - Slim Ibrahim
AU - Shengyi Shen
PY - 2026
DA - 2026/09/20
PB - arXiv
DO - 10.48550/arxiv.2609.23719
UR - https://arxiv.org/abs/2609.23719
AB - In this paper, we investigate the dynamics and long-time stability of hierarchical configurations in an N-point vortex system on ℝ^2 and in simply connected domains, without the Cantor-set restriction inherent in KAM theory. Since the Hamiltonian perturbation lacks a standard power-series expansion in the usual normalized variables, we develop a modified Birkhoff normal form based on successive ratios of adjacent variables, tailored to the hierarchical structure. A key feature is the preservation of the resulting natural exponent structure throughout the normal form procedure. Consequently, for n sufficiently large, the hierarchical configuration persists for times of order at least ε^−(n−2(N−1)).
ER -