Global Recovery from Local Data: Interior Nudging for 2D Navier-Stokes equations in a Physical Domain

Fuente: arXiv
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Autores principales: Fang, Rui, Pakzad, Ali
Formato: Preprint
Publicado: 2026
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author Fang, Rui
Pakzad, Ali
author_facet Fang, Rui
Pakzad, Ali
contents In many real-world applications of data assimilation (DA), the strategic placement of observers is crucial for effective and efficient forecasting. Motivated by practical constraints in sensor deployment, we show that global recovery of the flow field can be achieved using observations available only in a subregion of the domain, possibly far from the boundary. We focus on the two-dimensional incompressible Navier-Stokes equations posed in a bounded physical domain with Dirichlet boundary conditions. Building on the continuous data assimilation framework of Azouani, Olson, and Titi (2014), we rigorously prove that the assimilated solution converges globally to the true solution under suitable conditions on the nudging parameter, spatial resolution, and the geometry of the observation region, specifically, when the maximum distance from any point in the domain to the observational subregion is bounded by a constant multiple of \( ν^{1/2} \) (in terms of scaling). Our computational results, conducted via finite element methods over complex geometries, support the theoretical findings and reveal even greater robustness in practice. Specifically, synchronization with the true solution is achieved even when the observational subregion lies farther from the rest of the domain than the theoretical threshold permits. Across all three tested scenarios, the local nudging algorithm performs comparably to full-domain assimilation, reaching global accuracy up to machine precision. Interestingly, observational data near the boundary are found to be largely uninformative. This demonstrates that full observability is not necessary: carefully chosen interior observations, even far from the boundary, can suffice.
format Preprint
id arxiv_https___arxiv_org_abs_2601_11831
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Global Recovery from Local Data: Interior Nudging for 2D Navier-Stokes equations in a Physical Domain
Fang, Rui
Pakzad, Ali
Numerical Analysis
Chaotic Dynamics
Fluid Dynamics
35Q30, 34D06, 35Q93, 93B07, 76D10
In many real-world applications of data assimilation (DA), the strategic placement of observers is crucial for effective and efficient forecasting. Motivated by practical constraints in sensor deployment, we show that global recovery of the flow field can be achieved using observations available only in a subregion of the domain, possibly far from the boundary. We focus on the two-dimensional incompressible Navier-Stokes equations posed in a bounded physical domain with Dirichlet boundary conditions. Building on the continuous data assimilation framework of Azouani, Olson, and Titi (2014), we rigorously prove that the assimilated solution converges globally to the true solution under suitable conditions on the nudging parameter, spatial resolution, and the geometry of the observation region, specifically, when the maximum distance from any point in the domain to the observational subregion is bounded by a constant multiple of \( ν^{1/2} \) (in terms of scaling). Our computational results, conducted via finite element methods over complex geometries, support the theoretical findings and reveal even greater robustness in practice. Specifically, synchronization with the true solution is achieved even when the observational subregion lies farther from the rest of the domain than the theoretical threshold permits. Across all three tested scenarios, the local nudging algorithm performs comparably to full-domain assimilation, reaching global accuracy up to machine precision. Interestingly, observational data near the boundary are found to be largely uninformative. This demonstrates that full observability is not necessary: carefully chosen interior observations, even far from the boundary, can suffice.
title Global Recovery from Local Data: Interior Nudging for 2D Navier-Stokes equations in a Physical Domain
topic Numerical Analysis
Chaotic Dynamics
Fluid Dynamics
35Q30, 34D06, 35Q93, 93B07, 76D10
url https://arxiv.org/abs/2601.11831