Application of particle image velocimetry and proper orthogonal decomposition to the study of a jet in a counterflow

Bernero, Stefano; Fiedler, H. E.

doi:10.1007/s003480070029

Cited by 79 publications

(37 citation statements)

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“…Unlike free jet, it barely affects the jet shearlayers and has its maximum at the centerline. The mode pair mode 1 and 3 can from this view be considered as a flapping motion, which is infact how they were interpreted by Bernero and Fiedler [1]. However, considering the modes in the plane perpendicular to the main flow direction one can clearly see that this is a rotation of the jet core.…”

supporting

confidence: 57%

“…single jet in quiescent environment, jet in cross-flow) have receive much attention whereas only few studies focused on the case of a jet issuing into a uniform counter-flow (JiCF). Among important studies, Bernero and Fiedler [1] evidenced some large scale flapping like motion but restricted their analysis to plane data. Tsunoda and Saruta [2] highlighted the bimodal shape of the scalar pdf as a consequence of the large scale fluctuation.…”

mentioning

confidence: 99%

“…We consider a set-up similar to the experiments conducted by Bernero and Fiedler [1]. The numerical setup models a jet of diameter D issuing into a counter-flow area of 10D*10D.…”

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confidence: 99%

“…The averages and POD modes are computed using around 1500 snapshots collected over 400T , where T = D/U 0. Since the incoming fluctuation intensity is barely detectable in the experiments of Bernero and Fiedler [1] we model the jet inflow by a laminar top-hat profile for the streamwise component of the velocity vector. The counter flow is laminar and uniform.…”

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confidence: 99%

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Large Scale Dynamics of a Jet in a Counter Flow

Duwig

Revstedt

2009

Springer Proceedings in Physics

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Numerous studies of turbulent jets have contributed to a better understanding of the flow physics with applications in vehicle engineering, power generation or chemical industry. Different configurations (e.g. single jet in quiescent environment, jet in cross-flow) have receive much attention whereas only few studies focused on the case of a jet issuing into a uniform counter-flow (JiCF). Among important studies, Bernero and Fiedler [1] evidenced some large scale flapping like motion but restricted their analysis to plane data. Tsunoda and Saruta [2] highlighted the bimodal shape of the scalar pdf as a consequence of the large scale fluctuation. The purpose of the present work is to forther increase the understanding of the JiCF with the focus on identifying the large scale coherent structures using 3D LES data. In the LES framework, we consider the filtered incompressible continuity and momentum equations [3]. The subgrid scale (SGS) term is modeled using a classical eddy viscosity type model based on the Filtered Structure Function Model by Ducros et al. [4]. To solve the filtered governing equations on Cartesian grids a high-order finite difference code is used.The spatial discretization is done using a fourth order centered scheme. However, for the convective terms a small portion of hyper-viscosity is added to the fourth order scheme, for stability reasons. A second order implicit finite difference scheme is used for time discretization. Multi-grid iterations are used to solve the implicit parts of the system. These advantages make the present approach suitable for LES of turbulent flows, in particular jets, e.g. Maciel et al. [5].A commonly followed post-processing procedure consists of computing mean and RMS fields of the velocity variables. However, information related to large scale coherent motions is lost. We seek to supplement the mean and RMS fields by employing Proper Orthogonal Decomposition (POD) and we focus on the most energetic eddies/modes. Consequently, one seeks to project the turbulent flow field on a vector base that maximizes the turbulent kinetic ⋆ also at Haldor Topsoe A/S, DK-2800 Lyngby

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supporting

confidence: 57%

mentioning

confidence: 99%

“…We consider a set-up similar to the experiments conducted by Bernero and Fiedler [1]. The numerical setup models a jet of diameter D issuing into a counter-flow area of 10D*10D.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

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Large Scale Dynamics of a Jet in a Counter Flow

Duwig

Revstedt

2009

Springer Proceedings in Physics

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“…Examples are Meyer et al [17], comparing PIV data with Large Eddy Simulations (LES), Bernero and Fiedler [3] on PIV data, and Tirunagari et al [30] on LES data. There is the need of using such a technique because the turbulent flow in the wake is chaotic and random, and POD allows the identification of the choerent structures and their classification by energy content [2].…”

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confidence: 99%

Unsteady aerodynamics of single and tandem wheels

Spagnolo

Zhang

et al. 2017

Journal of Fluids and Structures

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The major unsteady aerodynamic forces and major physics of a generic single wheel and tandem wheels are studied for the first time using wind tunnel tests. The wind-tunnel tests are performed in the 2.1 m × 1.5 m wind tunnel at the University of Southampton. The tandem-wheel configuration consists of two in-line wheels that can be tested at different inter-axis distances and various installation angles. A vibration test is performed in situ on the model assembly to validate the unsteady-load measurements. Mean and unsteady aerodynamic loads and on-surface pressures are measured. Particle Image Velocimetry is used to acquire the velocity fields in the wake downstream of the model and surface oil-flow technique is used to identify the flow features on the surface of the wheels. Proper Orthogonal Decomposition is also used to characterise the wake in terms of unsteady fluctuations. The results of the experiments on the tandem wheels show that higher values of inter-axis distance correspond to slightly higher total mean drag coefficients and remarkably lower drag coefficient RMS values. Higher installation angles are associated with higher mean drag coefficients but generally lower fluctuations of the force coefficients. Non-zero mean lift coefficients are found for low inter-axis distance configurations at zero installation angle. The flow on the single wheel and on the front wheel of the tandem wheels is affected by laminar-turbulent transitional features. The vortical structures past the tandem wheels consist of four vortices that detach from the tyre shoulders of the front wheel and interact with the rear wheel. The study and obtained databases contribute to the general understanding of the complex flow and help to improve engineering predication of the gear aerodynamic loads.

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Physical simulation of atmospheric microbursts

et al. 2014

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A laboratory simulation of atmospheric microbursts is presented. The physical model of the atmospheric phenomenon is reproduced at a reduced scale in a rotating tank (TURLab, Italy), the similitude is based on the Froude number. Different experiments were carried out varying the Rossby number, and the analysis of four significant cases is presented. The velocity, vorticity, and turbulent kinetic energy fields are evaluated together with the swirling strength analysis. The comparison with the natural prototype is eventually shown and discussed.

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Application of particle image velocimetry and proper orthogonal decomposition to the study of a jet in a counterflow

Cited by 79 publications

References 0 publications

Large Scale Dynamics of a Jet in a Counter Flow

Large Scale Dynamics of a Jet in a Counter Flow

Unsteady aerodynamics of single and tandem wheels

Physical simulation of atmospheric microbursts

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