Turbulence from an observer perspective

TA Zaki - Annual Review of Fluid Mechanics, 2024 - annualreviews.org
Turbulence is often studied by tracking its spatiotemporal evolution and analyzing the
dynamics of its different scales. The dual to this perspective is that of an observer who starts …

Estimating density, velocity, and pressure fields in supersonic flows using physics-informed BOS

JP Molnar, L Venkatakrishnan, BE Schmidt… - Experiments in …, 2023 - Springer
We report a new workflow for background-oriented schlieren (BOS), termed “physics-
informed BOS,” to extract density, velocity, and pressure fields from a pair of reference and …

State estimation in minimal turbulent channel flow: A comparative study of 4DVar and PINN

Y Du, M Wang, TA Zaki - International Journal of Heat and Fluid Flow, 2023 - Elsevier
The state of turbulent, minimal-channel flow is estimated from spatio-temporal sparse
observations of the velocity, using both a physics-informed neural network (PINN) and …

Unsteady flow enhancement on an airfoil using sliding window weak-constraint four-dimensional variational data assimilation

S Li, C He, Y Liu - Physics of Fluids, 2023 - pubs.aip.org
This study establishes a continuous sliding window weak-constraint four-dimensional
variational approach for reproducing a complete instantaneous flow from sparse …

Stochastic particle advection velocimetry (SPAV): theory, simulations, and proof-of-concept experiments

K Zhou, J Li, J Hong, SJ Grauer - Measurement Science and …, 2023 - iopscience.iop.org
Particle tracking velocimetry (PTV) is widely used to measure time-resolved, three-
dimensional velocity and pressure fields in fluid dynamics research. Inaccurate localization …

Four-dimensional variational data assimilation of a turbulent jet for super-temporal-resolution reconstruction

C He, X Zeng, P Wang, X Wen, Y Liu - Journal of Fluid Mechanics, 2024 - cambridge.org
The super-temporal-resolution (STR) reconstruction of turbulent flows is an important data
augmentation application for increasing the data reach in measurement techniques and …

Reconstruction of three-dimensional turbulent flow structures using surface measurements for free-surface flows based on a convolutional neural network

A Xuan, L Shen - Journal of Fluid Mechanics, 2023 - cambridge.org
A model based on a convolutional neural network (CNN) is designed to reconstruct the three-
dimensional turbulent flows beneath a free surface using surface measurements, including …

Flow enhancement from wall pressure observations: A compressible continuous adjoint data assimilation model

S Li, C He, W Wang, Y Liu - Physics of Fluids, 2023 - pubs.aip.org
This study establishes a compressible continuous adjoint data assimilation (C 2 ADA)
approach for reproducing a complete mean flow from sparse wall pressure observations …

ML for fast assimilation of wall-pressure measurements from hypersonic flow over a cone

P Morra, C Meneveau, TA Zaki - Scientific Reports, 2024 - nature.com
Data assimilation (DA) integrates experimental measurements into computational models to
enable high-fidelity predictions of dynamical systems. However, the cost associated with …

Nonlinear estimation in turbulent channel flows

J Ding, SJ Illingworth - arXiv preprint arXiv:2408.12827, 2024 - arxiv.org
We design a nonlinear estimator for channel flows at $ Re_ {\tau}= 180$ and $590 $. The
nonlinear estimator uses a linear estimator structure based on the linearised Navier-Stokes …