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In Hamiltonian systems subjected to periodic perturbations the stable and unstable manifolds of the unstable periodic orbits provide the dynamical "skeleton" that drives the mixing process and bounds the chaotic regions of the phase space.…

Plasma Physics · Physics 2016-10-05 David Ciro Taborda , Todd Edwin Evans , Iberê Luiz Caldas

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 equations and explicitly calculates the nonlinear forcing from…

Fluid Dynamics · Physics 2024-08-26 Jitong Ding , Simon J. Illingworth

A phase-field method for unstructured grids that is accurate, conservative, and robust is proposed in this work. The proposed method also results in bounded transport of volume fraction, and the interface thickness adapts automatically to…

Fluid Dynamics · Physics 2023-10-18 Hanul Hwang , Suhas S. Jain

A numerical framework for rigorous linear stability analysis of two-phase stratified flows of two immiscible fluids in horizontal circular pipes is presented. For the first time, three-dimensional disturbances, including those at the…

Fluid Dynamics · Physics 2023-07-17 Ilya Barmak , Alexander Gelfgat , Neima Brauner

We study stability and input-state analysis of three dimensional (3D) incompressible, viscous flows with invariance in one direction. By taking advantage of this invariance property, we propose a class of Lyapunov and storage functionals.…

Optimization and Control · Mathematics 2016-11-17 Mohamadreza Ahmadi , Giorgio Valmorbida , Antonis Papachristodoulou

This paper considers a Leray regularization model of incompressible, non-isothermal fluid flows which uses nonlinear filtering based on indicator functions, and introduces an efficient numerical method for solving it. The proposed method…

Numerical Analysis · Mathematics 2020-08-04 Mine Akbas , Abigail Bowers

Real-time motion detection in non-stationary scenes is a difficult task due to dynamic background, changing foreground appearance and limited computational resource. These challenges degrade the performance of the existing methods in…

Computer Vision and Pattern Recognition · Computer Science 2018-11-22 Junjie Huang , Wei Zou , Zheng Zhu , Jiagang Zhu

In recent years, the LiDAR images, as a 2D compact representation of 3D LiDAR point clouds, are widely applied in various tasks, e.g., 3D semantic segmentation, LiDAR point cloud compression (PCC). Among these works, the optical flow…

Image and Video Processing · Electrical Eng. & Systems 2021-08-31 Xuezhou Guo , Xuhu Lin , Lili Zhao , Zezhi Zhu , Jianwen Chen

We propose a deep probabilistic-neural-network architecture for learning a minimal and near-orthogonal set of non-linear modes from high-fidelity turbulent-flow-field data useful for flow analysis, reduced-order modeling, and flow control.…

Fluid Dynamics · Physics 2021-09-06 Hamidreza Eivazi , Soledad Le Clainche , Sergio Hoyas , Ricardo Vinuesa

In this paper we apply a reduced basis framework for the computation of flow bifurcation (and stability) problems in fluid dynamics. The proposed method aims at reducing the complexity and the computational time required for the…

Numerical Analysis · Mathematics 2018-01-04 Giuseppe Pitton , Gianluigi Rozza

In this work, we prove what appear to be the first Reynolds-semi-robust and pressure-robust velocity error estimates for an H(div)-conforming approximation of unsteady incompressible flows of power-law type fluids. The proposed methods…

Numerical Analysis · Mathematics 2025-05-14 Lourenço Beirão da Veiga , Daniele A. Di Pietro , Kirubell B. Haile

This study extends the flow measurement method initially proposed in [22] to three-dimensional scenarios, addressing the growing need for accurate and efficient non-contact flow measurement techniques in complex hydrodynamic environments.…

Numerical Analysis · Mathematics 2025-03-18 Jiwei Li , Lingyun Qiu , Zhongjing Wang , Hui Yu

The decay of a passive scalar in a three-dimensional chaotic flow is studied using high-resolution numerical simulations. The (volume-preserving) flow considered is a three-dimensional extension of the randomised alternating sine flow…

Chaotic Dynamics · Physics 2015-03-18 Keith Ngan , Jacques Vanneste

An analytical model for three-dimensional incompressible turbulence was recently introduced in the hydrodynamics community which, with only a few parameters, shares many properties of experimental and numerical turbulence, notably…

Astrophysics of Galaxies · Physics 2021-01-13 J. -B. Durrive , K. Ferrière , P. Lesaffre

We consider fluid flows for which the linearized Navier-Stokes operator is strongly non-normal. The responses of such flows to external perturbations are spanned by a generically very large number of non-orthogonal eigenmodes. They are…

Fluid Dynamics · Physics 2025-07-11 Yves-Marie Ducimetière , François Gallaire

Three-dimensional direct numerical simulations of an incompressible open square cavity flow are conducted. Features of the permanent (non-linear) regime together with the linear stability analysis of a two-dimensional steady base flow are…

Fluid Dynamics · Physics 2012-07-30 L. R. Pastur , Y. Fraigneau , F. Lusseyran , J. Basley

Phase-field methods have long been used to model the flow of immiscible fluids. Their ability to naturally capture interface topological changes is widely recognized, but their accuracy in simulating flows of real fluids in practical…

Fluid Dynamics · Physics 2019-06-10 Baofang Song , Carlos Plana , Jose M. Lopez , Marc Avila

We present and analyze a penalization method wich extends the the method of [1] to the case of a rigid body moving freely in an incompressible fluid. The fluid-solid system is viewed as a single variable density flow with an interface…

Analysis of PDEs · Mathematics 2009-01-15 Claire Bost , Georges-Henri Cottet , Emmanuel Maitre

We study the instantaneous inference of an unbounded planar flow from sparse noisy pressure measurements. The true flow field comprises one or more regularized point vortices of various strength and size. We interpret the true flow's…

Fluid Dynamics · Physics 2024-05-08 Jeff D. Eldredge , Mathieu Le Provost

This paper proposes an Extended-Kalman-Filter-like observer for parameter estimation during synchronization of chaotic systems. The exponential stability of the observer is guaranteed by a persistent excitation condition. This approach is…

Chaotic Dynamics · Physics 2017-06-21 L. Torres