Toward Better Understanding of Turbulence Effects on Bridge Aerodynamics

Cao, Shuyang; Cao, Jun

doi:10.3389/fbuil.2017.00072

Cited by 7 publications

(3 citation statements)

References 11 publications

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“…circular) and bridge-deck cross section, and the considerably less number of studies on the latter than those on the former. Cao et al (2017) reviewed a number of cases for the circular cylinder. They suggested that turbulence has a very strong influence on the extension of the lock-in region, and in some cases, turbulence can completely suppress the structure's response.…”

Section: Freestream Turbulence Effects On the Amplitude Of Viv Responsementioning

confidence: 99%

Overview of large-eddy simulation for wind loading on slender structures

Daniels¹,

Xie²

2022

Proceedings of the Institution of Civil Engineers - Engineering

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Understanding and predicting the effects of wind loading on a structure is necessary for a safe, effective, and economical engineering design. Wind tunnel techniques are expensive and often provide data that is not sufficiently detailed for the structural engineer. With increasing advances in computational capabilities, it has recently become feasible to investigate these flows using numerical techniques. Of these, one of the most effective approaches to simulate the turbulence observed in natural wind is Large-Eddy Simulation (LES). The application of LES to analyse wind loading, and aeroelastic effects on structures are only a recent venture in the field. This paper reviews the progress made over the last few decades for the analysis of wind flow around slender structures, and the more recent analysis incorporating the effects of freestream turbulence. Firstly, a review of the literature for generating freestream turbulence is carried out, and are assessed based on their flaws and strengths. A number of these are subsequently used for the analysis of surface pressures on an isolated tall model building. Subsequently, a review is made into wind tunnel analysis and LES for the aeroelastic analysis of bridge sections. The recent advances in the understanding of turbulence effects on the aeroestatic responses are summarised. The future of LES and its relationship wind tunnel analysis for wind loading analysis are discussed.

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Section: Freestream Turbulence Effects On the Amplitude Of Viv Responsementioning

confidence: 99%

Overview of large-eddy simulation for wind loading on slender structures

Daniels¹,

Xie²

2022

Proceedings of the Institution of Civil Engineers - Engineering

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“…Anyways, the answer shall not necessarily be dichotomic; at least, the influence of turbulence should depend on the type of turbulence (its frequency content) and its intensity. In some studies, turbulence is shown to have a strong effect on the synchronization mechanism and may lead to a complete suppression of VIV (Cao and Cao, 2017). Other works tend to indicate that the grid turbulence of the oncoming flow has virtually no influence on the response amplitude (Goswami et al, 1993).…”

Section: Introductionmentioning

confidence: 99%

Derivation of a slow phase model of vortex-induced vibrations for smooth and turbulent oncoming flows

Denoël

2020

Journal of Fluids and Structures

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This paper analyzes the influence of turbulence on a wake-oscillator model. Turbulence is introduced by randomizing the model proposed by Facchinetti et al. under the quasisteady assumption. A multiple scale analysis of the deterministic model shows that the response is governed by a dimensionless group D, expressed as a function of the amplitudes of the forcing terms in the two governing equations, the total (aerodynamic plus structural) damping and the parameter ε of the fluid Van der Pol oscillator. The influence of turbulence is interpreted as a stochastic noise of small intensity and with a slower timescale than the (fast) oscillations, which is typical of wind engineering applications. A slow phase model of the problem is then derived by assuming that the small turbulence drives the system only slightly away from its limit cycle in smooth flow conditions. Standard modeling techniques borrowed from other fields of physics, in particular the observation of phase shifts and their accumulation, are used to highlight conditions under which the turbulence of the oncoming flow might reduce the amplitudes of vibrations of the body. The slow phase model is derived in smooth flow conditions, then extended to turbulent flow. It recalls that the phase plays a central role in synchronization problems, and that the response amplitude should only be considered as a sub-product of the slow phase. The slow phase model is expressed by means of a first order nonlinear differential equation for the phase and a memoryless transformation for the response amplitudes. Its solution is explicit and simple in some limiting cases. In particular, for small turbulence intensity, the response is shown to be insensitive to turbulence when its frequency content is not low enough. This major dependence upon the frequency content of the turbulence explains that the reduction of VIV due to turbulence cannot be explained by the turbulence intensity only, as usually considered today. The required relative smallnesses of the turbulence and its frequency content naturally appear in the derivation, which is led in a dimensionless manner. Finally, the present study constitutes an analysis of a phenomenological model which could be used in a much wider concept than of the elastically-mounted circular cylinder.

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“…Furthermore, Cao, S. and Cao, J. [5] briefly introduced a newly developed multiple-fan wind tunnel which is designed to control turbulence to assist the study of turbulence effects. Wang, J.Y, Meng, Q. H., Luo, B. and Zeng, M. [6] presented a new type of active controlled multiple-fan wind tunnel.…”

Section: Introductionmentioning

confidence: 99%

A Low-Cost Active Control Multi-Fan Turbulence Wind Tunnel with an Embedded System to Generate Natural Wind

Kikuchi¹,

Matsubara²,

Pornthisarn³

et al. 2019

OJFD

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This paper describes a new actively controlled multi-fan wind tunnel that generates natural wind as a type of turbulence wind tunnel at a reduced cost. The driving section of the wind tunnel has 100 PC cooling fans that are controlled by an original embedded system. The fluctuating velocity wind is successfully generated with a mean velocity of 7 m/s and two turbulent intensities of 2% and 3% based on Karman's power spectrum density function. The case of 2% has the integral scales of 5 m, 10m and 20 m, and the case of 3% has the integral scales of 3 m, 6 m and 15 m with a turbulence grid. In particular, the wind with the turbulent intensity of 2% satisfies the Kolmogorov's −5/3 multiplication rule of inertial subrange with the frequency range from 0.01 Hz to 2.0 Hz. Consequently, the new wind tunnel can be used for studying engineering technology and research regarding conditions with natural wind.

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Toward Better Understanding of Turbulence Effects on Bridge Aerodynamics

Cited by 7 publications

References 11 publications

Overview of large-eddy simulation for wind loading on slender structures

Overview of large-eddy simulation for wind loading on slender structures

Derivation of a slow phase model of vortex-induced vibrations for smooth and turbulent oncoming flows

A Low-Cost Active Control Multi-Fan Turbulence Wind Tunnel with an Embedded System to Generate Natural Wind

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