Comparison of flow characteristics around an equilateral triangular cylinder via PIV and Large Eddy Simulation methods

Yagmur, Sercan; Doğan, Sercan; Aksoy, Muharrem Hilmi; Göktepeli, İlker; Özgören, Muammer

doi:10.1016/j.flowmeasinst.2017.04.001

Cited by 47 publications

(23 citation statements)

References 47 publications

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“…At α = 0 • the mean flow is symmetrical and two vortices are formed behind the three-rib cylinder(figure 15 a). This is consistent with experimental and numerical results byYagmur et al (2017) for a triangular prism at the same angular orientation. With the increase of angle of attack the symmetry is broken and an additional vortex starts to form in the top cavity (figure 15 b).…”

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confidence: 92%

Angle of attack dependence of flow past cactus-inspired cylinders with a low number of ribs

Zhdanov

Busse

2019

European Journal of Mechanics - B/Fluids

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The aerodynamic coefficients and the Strouhal number of cylinders with three and four ribs, inspired by succulents Euphorbia trigona and Euphorbia Abyssinica are investigated using 2D Unsteady Reynolds-Averaged Navier-Stokes simulations at Reynolds number 20,000. Both configurations show a significant dependence of the studied characteristics on the angle of attack. The obtained results are compared to the smooth circular cylinder, previous results for cylinders with 24 ribs based on the Saguaro cactus, and cylinders with triangular and square cross-sections. Relative to the circular cylinder, the mean drag coefficient is lowered only for the four-rib case at high angles of attack. However, at some angular positions, the ability to reduce unsteady force fluctuations exceeds Saguaro-inspired cylinders. For both shapes studied, the Strouhal number at most angles of attack is lower compared to both the circular cylinder and cylinders with 24 ribs at the same Reynolds number. The minimum values of the aerodynamic coefficients for both configurations are related to the angular orientation. For the four-rib case a critical angle of α cr ≈ 40 • is observed, at which the mean drag coefficient and the fluctuating lift coefficient attain their minima. The mean lift coefficient reaches at this angle its maximum value before a sudden drop for higher angles of attack. Therefore, for cactus-shaped cylinders with four ribs high angles of attack give the optimum orientation relative to prevailing winds.

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confidence: 92%

Angle of attack dependence of flow past cactus-inspired cylinders with a low number of ribs

Zhdanov

Busse

2019

European Journal of Mechanics - B/Fluids

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“…They also found that cellular structures with lower shed-ding frequencies than the Kármán vortex shedding frequency are generated in the wake due to the interference of the free-end vortex pair or the base vortex pair. Yagmur et al 6 studied a corner oriented equilateral triangular cylinder using Particle Image Velocimetry (PIV) and LES. They found that increasing Re leads to a shrunk wake and backside approached stagnation points.…”

Section: Introductionmentioning

confidence: 99%

Large eddy simulation of incident flows around polygonal cylinders

2021

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In this study, we carry out large eddy simulation (LES) of incident flow around polygonal cylinders of side number N = 5 − 8 at Reynolds number Re= 10 4 . In total, six incidence angles (α) are studied on each cylinder ranging from face to corner orientations, thus covering the entire α spectrum. Special focus is put on the time-mean aerodynamic forces including lift, drag and vortex shedding frequencies as well as the near wake flow features. It is found that because of y-plane asymmetry of polygonal cross sections at most incidence angles, the flow separation characteristics and hence the induced base pressure distribution and the aerodynamic forces exhibit unique and complex dependence on α and N. While the general inverse relation of drag coefficient and Strouhal number previously proposed from experimental observations at principal orientations still holds at arbitrary α, the variation of the two is found to be non-monotonic on both α and N. We also found that compared to the absolute time mean shear layer length measured from the final separation point, the extent of them stretched to the wake, measured from the cylinder centre, is a powerful scaling factor for all the quantities investigated, including the wake characteristic length scales. In particular, the difference between the top and the bottom shear layer (due to geometrical asymmetry at arbitrary α) describes the variation of the non-zero time mean lift coefficient reasonably well, whose sign varies with N non-monotonically.

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“…For 2-D triangular prisms, numerical and experimental studies at Re = 520 (Agrwal, Dutta & Gandhi 2016) and Re 10 4 (Yagmur et al 2017) have shown that the vortex formation and shedding process is similar to that described by Gerrard (1966). However, the vortex formation and shedding process for 3-D cantilevered triangular prisms has not been characterized.…”

Section: Resultsmentioning

confidence: 99%

Investigation of the influence of low-frequency forcing on the 3-D turbulent wake of a cantilevered triangular prism

2021

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Comparison of flow characteristics around an equilateral triangular cylinder via PIV and Large Eddy Simulation methods

Cited by 47 publications

References 47 publications

Angle of attack dependence of flow past cactus-inspired cylinders with a low number of ribs

Angle of attack dependence of flow past cactus-inspired cylinders with a low number of ribs

Large eddy simulation of incident flows around polygonal cylinders

Investigation of the influence of low-frequency forcing on the 3-D turbulent wake of a cantilevered triangular prism

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