Numerical simulation of vortex shedding past triangular cylinders at high Reynolds number using a <i>k</i>‐ε turbulence model

Johansson, Stefan; Davidson, Lars; Olsson, Erik

doi:10.1002/fld.1650161002

Cited by 63 publications

(27 citation statements)

References 7 publications

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“…In contrast to the research related to the flow past circular and rectangular section cylinders, there are limited studies that focus on a triangular cylinder immersed in a uniform flow because the triangular prism is seldom used in building structures. Several researchers have emphasized the influence of the wind direction and the cross-sectional shape on the flow past a triangular cylinder [23][24][25][26]. They demonstrated that the fluctuating cross-flow forces connected with the vortex shedding vary significantly with the incident flow orientation and the aspect ratio.…”

Section: Introductionmentioning

confidence: 99%

Flow Induced Vibration and Energy Extraction of an Equilateral Triangle Prism at Different System Damping Ratios

et al. 2016

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Abstract:The flow induced vibration and energy extraction of an equilateral triangle prism elastically mounted in a water channel are investigated experimentally at different system damping ratios ζ total with the constant oscillating mass M osc and system stiffness K. A power take-off system with a variable damping function is developed. The translation-rotation equation of the vibration system deduced in the study indicates that the total oscillating mass includes the material mass, and the equivalent mass due to the rotation of the gears and rotor. Besides, increasing load resistance can result in a decrease in ζ total when K and M osc remain unchanged. The prism experiences, in turn, soft galloping, hard galloping 1 and hard galloping 2 with increasing ζ total . As ζ total increases up to 0.335, only the vortex-induced vibration is observed because the extremely high ζ total prevents the prism from galloping. The response amplitude decreases with the increasing ζ total . In addition, higher ζ total promotes the galloping to start at a higher reduced velocity. The galloping characteristics of the prism, including large amplitude responses in an extremely large range of flow velocities, excellent vibration stationarity, and steady vibration frequencies, are beneficial for improving energy conversion. The prism can extract hydraulic energy for the flow velocity U > 0.610 m/s. The harnessed power P out and the energy conversion efficiency η out increase with increasing ζ total in the galloping zone. The maximum P out and η out reach 53.56 W and 40.44%, respectively. The optimal system damping ratio for extracting energy is the maximum system damping ratio that the prism can overcome to experience stable galloping.

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Section: Introductionmentioning

confidence: 99%

Flow Induced Vibration and Energy Extraction of an Equilateral Triangle Prism at Different System Damping Ratios

et al. 2016

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“…Bao et al (2010) considered flow over an equilateral triangular cylinder with different incidence angles at low Reynolds number range. Johansson et al (2010) studied the vortex shedding past triangular cylinders using a k-ε model of turbulence. Wei et al (2016) developed an hybrid RANS/LES model to simulate the complex turbulent flow around a triangular cylinder.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of Flow Past Two Transversely Oscillating Triangular Cylinders in Tandem at Low Reynolds Number

Zhai

Wang

2017

JAFM

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Flow past two tandem triangular cylinders forced to oscillate transversely in a uniform flow, is numerically investigated at a Reynolds number Re = 100. The incompressible Navier-Stokes equations in ArbitraryLagrangian-Eulerian formulation are solved by four-step fractional finite element method. The two cylinders are oscillated in phase and their motions are limited to low amplitudes with a wide frequency range. This study focuses on two typical spacings between the two cylinders, corresponding to vortex suppression (VS) regime and vortex formation (VF) regime respectively for flow past two stationary cylinders. Numerical results show that the response characteristics of two cylinders are significantly affected by the spacing, oscillation amplitude and frequency. For the VS spacing, both cylinders have a wider lock-on region, especially at relatively larger amplitude and higher frequency; the downstream wake patterns are mainly 2S and a combination of 2S* and 2S. However, for the VF spacing, the lock-on frequency range of the cylinders is even slightly narrower than that of a single oscillating cylinder; the wake field is more complex since it may comprises 2S, P+S and 2S* structures at some higher frequencies. Additionally, the hydrodynamic forces are also discussed in terms of mean and root mean square quantities, and reveal large differences between oscillating and stationary cylinders.

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“…This challenge comes from the fact that the separation is induced by the shock wave and not the geometry. Although URANS is shown to be pretty successful in predicting shedding from bluff bodies, 6 it becomes less reliable in problems where separation is caused otherwise. Flow oscillation over the circular arc airfoil is solved before using very primitive turbulence models like Baldwin-Lomax in two dimensions 5 but to the knowledge of the authors, it has never been solved by more advanced turbulence models such as SA or SST turbulence models as well as more complex models like DES.…”

Section: Introductionmentioning

confidence: 99%

Computation of Self-Excited Unsteady Transonic Flow of An Airfoil in a Channel Using URANS and DES

Xiong

Nezhad

Liu

2010

40th Fluid Dynamics Conference and Exhibit

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The performance of four different turbulence models in addressing shock wave-boundary layer instabilities is investigated. The problem chosen for this goal is a transonic flow over a 10% thick circular arc airfoil in a channel. The self-excited shock motion over the circular arc airfoil has been investigated before experimentally and those results are used as a benchmark for current study. Unsteady RANS and DES methods in combination with different turbulence models are used. All the methods can successfully predict the overall shock oscillatory behavior. Yet there are minor differences in frequency prediction. Another reason for choosing this problem is to better understand the physics governing the problem. It is found that the shock oscillation frequency strongly depends on mean shock wave location.

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Numerical simulation of vortex shedding past triangular cylinders at high Reynolds number using a k‐ε turbulence model

Cited by 63 publications

References 7 publications

Flow Induced Vibration and Energy Extraction of an Equilateral Triangle Prism at Different System Damping Ratios

Flow Induced Vibration and Energy Extraction of an Equilateral Triangle Prism at Different System Damping Ratios

Numerical Study of Flow Past Two Transversely Oscillating Triangular Cylinders in Tandem at Low Reynolds Number

Computation of Self-Excited Unsteady Transonic Flow of An Airfoil in a Channel Using URANS and DES

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