Interpretable structural model error discovery from sparse assimilation increments using spectral bias‐reduced neural networks: A quasi‐geostrophic turbulence test …

R Mojgani, A Chattopadhyay… - Journal of Advances in …, 2024 - Wiley Online Library
Earth system models suffer from various structural and parametric errors in their
representation of nonlinear, multi‐scale processes, leading to uncertainties in their long …

Identifying the body force from partial observations of a two-dimensional incompressible velocity field

A Farhat, A Larios, VR Martinez, JP Whitehead - Physical Review Fluids, 2024 - APS
Using limited observations of the velocity field of the two-dimensional Navier-Stokes
equations, we successfully reconstruct the steady body force that drives the flow. The …

Numerical solutions and analytical methods for the Kuralay equation: a path to understanding integrable systems

SH Alfalqi, MMA Khater - Optical and Quantum Electronics, 2024 - Springer
This study undertakes the challenging task of unraveling the intricacies embedded in the
integrable Kuralay equation, a cornerstone in the field of mathematical physics. Specifically …

Super-Exponential Convergence Rate of a Nonlinear Continuous Data Assimilation Algorithm: The 2D Navier–Stokes Equation Paradigm

E Carlson, A Larios, ES Titi - Journal of Nonlinear Science, 2024 - Springer
We study a nonlinear-nudging modification of the Azouani–Olson–Titi continuous data
assimilation (downscaling) algorithm for the 2D incompressible Navier–Stokes equations …

The bleeps, the sweeps, and the creeps: Convergence rates for dynamic observer patterns via data assimilation for the 2D Navier–Stokes equations

T Franz, A Larios, C Victor - Computer Methods in Applied Mechanics and …, 2022 - Elsevier
We adapt a continuous data assimilation scheme, known as the Azouani–Olson–Titi (AOT)
algorithm, to the case of moving observers for the 2D incompressible Navier–Stokes …

Determining modes, synchronization, and intertwinement

E Carlson, A Farhat, VR Martinez, C Victor - arxiv preprint arxiv …, 2024 - arxiv.org
This article studies the interrelation between the determining modes property in the two-
dimensional (2D) Navier-Stokes equations (NSE) of incompressible fluids and the …

On the infinite-nudging limit of the nudging filter for continuous data assimilation

E Carlson, A Farhat, VR Martinez, C Victor - arxiv preprint arxiv …, 2024 - arxiv.org
This article studies the intimate relationship between two filtering algorithms for continuous
data assimilation, the synchronization filter and the nudging filter, in the paradigmatic context …

Data assimilation with model error: Analytical and computational study for Sabra shell model

N Chen, A Farhat, E Lunasin - Physica D: Nonlinear Phenomena, 2023 - Elsevier
Understanding the impact of model error on data assimilation is an important practical topic.
Model error in the subgrid scale is commonly seen in various applications as a natural …

The second-best way to do sparse-in-time continuous data assimilation: Improving convergence rates for the 2D and 3D Navier-Stokes equations

A Larios, Y Pei, C Victor - arxiv preprint arxiv:2303.03495, 2023 - arxiv.org
We study different approaches to implementing sparse-in-time observations into the the
Azouani-Olson-Titi data assimilation algorithm. We propose a new method which introduces …

Mori-zwanzig latent space koopman closure for nonlinear autoencoder

P Gupta, PJ Schmid, D Sipp, T Sayadi… - arxiv preprint arxiv …, 2023 - arxiv.org
The Koopman operator presents an attractive approach to achieve global linearization of
nonlinear systems, making it a valuable method for simplifying the understanding of complex …