Effective dynamics and defect expansions for polynomial PDEs on thin annuli

Fuente: arXiv
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Main Author: Magnot, Jean-Pierre
Format: Preprint
Published: 2026
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author Magnot, Jean-Pierre
author_facet Magnot, Jean-Pierre
contents We develop a geometric and analytic framework for polynomial partial differential equations posed on thin annuli in the plane. Using renormalized Sobolev inner products, we construct Sobolev orthogonal polynomial bases adapted to the thin geometry and use them to define stable Galerkin approximations. We prove a general dimension-reduction theorem for polynomial Hamiltonian and dissipative PDEs, showing that solutions converge to effective one-dimensional dynamics on the limiting circle. Beyond the leading-order limit, we identify transverse defect correctors and derive cell problems describing anisotropic dispersive and homogenized effects. Our framework applies uniformly to integrable models (KdV, modified KdV, nonlinear Schrödinger, sine--Gordon), anisotropic dispersive systems such as Zakharov--Kuznetsov, and non-integrable perturbations including dissipation, forcing, and rapidly oscillating coefficients. We establish stability of the effective dynamics under changes of Sobolev order and of polynomial Hilbert geometry, and show robustness of the associated Galerkin schemes. The results provide a unified geometric perspective on dimension reduction, homogenization, and integrability in thin geometries, and introduce Sobolev orthogonal polynomial methods as a constructive tool for multiscale PDE analysis.
format Preprint
id arxiv_https___arxiv_org_abs_2602_12308
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Effective dynamics and defect expansions for polynomial PDEs on thin annuli
Magnot, Jean-Pierre
Exactly Solvable and Integrable Systems
High Energy Physics - Theory
Mathematical Physics
Analysis of PDEs
Optimization and Control
35B27, 35Q53, 35Q55, 35B45, 41A10, 42C05
We develop a geometric and analytic framework for polynomial partial differential equations posed on thin annuli in the plane. Using renormalized Sobolev inner products, we construct Sobolev orthogonal polynomial bases adapted to the thin geometry and use them to define stable Galerkin approximations. We prove a general dimension-reduction theorem for polynomial Hamiltonian and dissipative PDEs, showing that solutions converge to effective one-dimensional dynamics on the limiting circle. Beyond the leading-order limit, we identify transverse defect correctors and derive cell problems describing anisotropic dispersive and homogenized effects. Our framework applies uniformly to integrable models (KdV, modified KdV, nonlinear Schrödinger, sine--Gordon), anisotropic dispersive systems such as Zakharov--Kuznetsov, and non-integrable perturbations including dissipation, forcing, and rapidly oscillating coefficients. We establish stability of the effective dynamics under changes of Sobolev order and of polynomial Hilbert geometry, and show robustness of the associated Galerkin schemes. The results provide a unified geometric perspective on dimension reduction, homogenization, and integrability in thin geometries, and introduce Sobolev orthogonal polynomial methods as a constructive tool for multiscale PDE analysis.
title Effective dynamics and defect expansions for polynomial PDEs on thin annuli
topic Exactly Solvable and Integrable Systems
High Energy Physics - Theory
Mathematical Physics
Analysis of PDEs
Optimization and Control
35B27, 35Q53, 35Q55, 35B45, 41A10, 42C05
url https://arxiv.org/abs/2602.12308