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We analyze the performance of a data-assimilation algorithm based on a linear feedback control when used with observational data that contains measurement errors. Our model problem consists of dynamics governed by the two-dimension…

Analysis of PDEs · Mathematics 2015-06-19 Hakima Bessaih , Eric Olson , E. S. Titi

Continuous data assimilation (CDA) is a method that continuously integrates observational data into a dynamical system to improve model accuracy in real-time. The AOT algorithm is one of the most widely used methods in CDA due to its…

Optimization and Control · Mathematics 2024-07-25 Ning Ning , Collin Victor

In this paper we present two results: (1) A data assimilation algorithm for the 3D Navier-Stokes equation (3D NSE) using nodal data, and, as a consequence (2) a novel regularity criterion for the 3D NSE based on finitely many observations…

Analysis of PDEs · Mathematics 2022-11-29 Abhishek Balakrishna , Animikh Biswas

Motivated by the presence of a finite number of determining parameters (degrees of freedom) such as modes, nodes and local spatial averages for dissipative dynamical systems, we present a continuous data assimilation algorithm for the…

Analysis of PDEs · Mathematics 2014-08-26 Débora A. F. Albanez , Helena J. Nussenzveig Lopes , Edriss S. Titi

In this work, we study the applicability of the Azouani-Olson-Titi (AOT) nudging algorithm for continuous data assimilation to evolutionary dynamical systems that are not dissipative. Specifically, we apply the AOT algorithm to a partially…

Optimization and Control · Mathematics 2025-09-25 Edriss S. Titi , Collin Victor

We consider a non-linear Bayesian data assimilation model for the periodic two-dimensional Navier-Stokes equations with initial condition modelled by a Gaussian process prior. We show that if the system is updated with sufficiently many…

Statistics Theory · Mathematics 2024-07-10 Richard Nickl , Edriss S. Titi

The Reynolds-averaged Navier-Stokes (RANS) equations provide a computationally efficient method for solving fluid flow problems in engineering applications. However, the use of closure models to represent turbulence effects can reduce their…

Fluid Dynamics · Physics 2024-05-02 Oliver Brenner , Justin Plogmann , Pasha Piroozmand , Patrick Jenny

The error analysis of a proper orthogonal decomposition (POD) data assimilation (DA) scheme for the Navier-Stokes equations is carried out. A grad-div stabilization term is added to the formulation of the POD method. Error bounds with…

Numerical Analysis · Mathematics 2020-04-21 Bosco García Archilla , Julia Novo , Samuele Rubino

We study a continuous data assimilation (CDA) algorithm for a velocity-vorticity formulation of the 2D Navier-Stokes equations in two cases: nudging applied to the velocity and vorticity, and nudging applied to the velocity only. We prove…

Numerical Analysis · Mathematics 2020-06-15 Matthew Gardner , Adam Larios , Leo G. Rebholz , Duygu Vargun , Camille Zerfas

We study the immersed boundary problem in 2-D. It models a 1-D elastic closed string immersed and moving in a fluid that fills the entire plane, where the fluid motion is governed by the 2-D incompressible Navier-Stokes equation with a…

Analysis of PDEs · Mathematics 2025-12-17 Jiajun Tong , Dongyi Wei

We consider nonlinear solvers for the incompressible, steady (or at a fixed time step for unsteady) Navier-Stokes equations in the setting where partial measurement data of the solution is available. The measurement data is…

Numerical Analysis · Mathematics 2024-01-15 Bosco Garcia-Archilla , Xuejian Li , Julia Novo , Leo Rebholz

Data assimilation methodologies are designed to incorporate noisy observations of a physical system into an underlying model in order to infer the properties of the state of the system. Filters refer to a class of data assimilation…

Optimization and Control · Mathematics 2011-10-13 C. E. A. Brett , K. F. Lam , K. J. H. Law , D. S. McCormick , M. R. Scott , A. M. Stuart

We demonstrate a formulation of the Azouani-Olson-Titi (AOT) algorithm in the MPAS-Ocean implementation of the primitive equations of the ocean, presenting global ocean simulations with realistic coastlines and bathymetry. We observe an…

Analysis of PDEs · Mathematics 2024-01-12 Adam Larios , Mark R. Petersen , Collin Victor

This work investigates the effectiveness of the Back-and-Forth Nudging (BFN) data assimilation algorithm, specifically its performance when employing the Azouani-Olson-Titi (AOT) continuous data assimilation downscaling nudging algorithm,…

Analysis of PDEs · Mathematics 2026-04-23 Aseel Farhat , Edriss S. Titi , Collin Victor

In atmospheric and turbulent flow modeling, Large Eddy Simulation (LES) is often used to reduce computational cost, while observational data typically originates from the underlying physical system. Motivated by this setting, we study a…

Analysis of PDEs · Mathematics 2025-08-12 Adam Larios , Ali Pakzad , Nicholas White

This paper proposes a new data assimilation method for recovering high fidelity turbulent flow field around airfoil at high Reynolds numbers based on experimental data, which is called Proper Orthogonal Decomposition Inversion…

Fluid Dynamics · Physics 2020-07-14 Yilang Liu , Weiwei Zhang

We consider the Cauchy problem for the incompressible homogeneous Navier-Stokes (NS) equations on a d-dimensional torus, in the C^infinity formulation described, e.g., in [25]. In [22][25] it was shown how to obtain quantitative estimates…

Analysis of PDEs · Mathematics 2015-07-09 Carlo Morosi , Mario Pernici , Livio Pizzocchero

Based on a previously introduced downscaling data assimilation algorithm, which employs a nudging term to synchronize the coarse mesh spatial scales, we construct a determining map for recovering the full trajectories from their…

Analysis of PDEs · Mathematics 2018-01-04 Animikh Biswas , Ciprian Foias , Cecilia F. Mondaini , Edriss S. Titi

We propose a continuous data assimilation (CDA) method to address the uniqueness problem for steady Navier-Stokes equations(NSE). The CDA method incorporates spatial observations into the NSE, and we prove that with sufficient observations,…

Analysis of PDEs · Mathematics 2023-07-20 Xuejian Li

We propose, analyze, and test a novel continuous data assimilation two-phase flow algorithm for reservoir simulation. We show that the solutions of the algorithm, constructed using coarse mesh observations, converge at an exponential rate…

Numerical Analysis · Mathematics 2022-06-22 Yat Tin Chow , Wing Tat Leung , Ali Pakzad