Critical effects of a spanwise surface wire on flow past a circular cylinder and the significance of the wire size and Reynolds number

Aydın, Taner; Joshi, Antrix; Ekmekci, Alis

doi:10.1016/j.jfluidstructs.2014.08.006

Cited by 9 publications

(9 citation statements)

References 21 publications

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“…The subsequent work conducted by Ekmekci & Rockwell (2011) proved that only a spanwise surface wire that is larger than the boundary layer thickness can attenuate or intensify the Kármán instability at the critical locations, while a surface wire that is smaller than the boundary layer thickness was found to have no detectable impact on the strength and coherence of the Kármán vortex shedding. Soon after, Aydin, Joshi & Ekmekci (2014) confirmed that a single spanwise surface wire stops the regular formation of Kármán vortices over long periods of time when placed at a first critical wire location , but the regular shedding still resumes intermittently for short times. As a result, in the time-averaged sense, a drastic attenuation is observed in the autospectral density of velocity fluctuations at the frequency of Kármán vortex shedding.…”

Section: Introductionmentioning

confidence: 89%

“…This inference is based on the boundary layer thickness data provided by Aydin et al . (2014). For experiments where the VIV response branches of the plain cylinder (without a surface wire) were investigated by collecting the amplitude versus reduced velocity data, a free-stream velocity range of to was used, corresponding to a Reynolds number range of to .…”

Section: Experimental Set-upmentioning

confidence: 99%

“…This endplate design is consistent with those used in the previous literature for stationary cylinders (Ekmekci 2006; Ekmekci & Rockwell 2010; Aydin et al . 2014; Joshi & Ekmekci 2019). For all experiments involving free oscillations of the cylinder, a gap equal to 13.8 % of the cylinder diameter (a gap spacing of 7 mm) was left between the bottom end of the cylinder and the endplate to induce conditions of a free-ended cylinder in accord with Morse et al .…”

Section: Experimental Set-upmentioning

confidence: 99%

“…Also, Aydin et al . (2014) investigated the dependence of the critical wire locations on the wire size and Reynolds number (within the subcritical Reynolds number range of to ). Their results indicated that the range of is generally independent of both the Reynolds number and wire size, while the range of depends on the wire size, and for a given wire size, increases with increasing Reynolds number until the Reynolds number of is reached, beyond which becomes independent of the Reynolds number within the range that they studied.…”

Section: Introductionmentioning

confidence: 99%

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Effects of a single spanwise surface wire on a free-ended circular cylinder undergoing vortex-induced vibration in the lower synchronization range

Vaziri

Ekmekci

2022

J. Fluid Mech.

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This experimental study investigated the control induced by a spanwise surface wire on a rigid circular cylinder undergoing vortex-induced vibration (VIV) under the conditions of low mass damping in the lower synchronization branch. Being motivated by the idea of VIV-based energy harvesting from ocean and river flows, this elastically mounted cylinder was immersed in a water channel, leaving a free end at its bottom spanwise end, while the free water surface bounded its top. The cylinder was constrained to vibrate in the cross-stream direction. The wire diameter was 6.25 % of the cylinder diameter. Experimental research was conducted by attaching this large-scale wire along the span of the cylinder at various angular positions ranging from 0° to 180° (with respect to the most upstream point of the cylinder) at a fixed Reynolds number of 104 (based on the cylinder diameter). Simultaneous to measuring the trajectory of the cylinder motion via a laser distance sensor, the instantaneous velocity field in the near wake of the cylinder was obtained using particle image velocimetry. Several VIV response categories were identified depending on the angular position of the wire, which led to the classification of distinct angular ranges for the wire application. Associated with the structural vibrations in these categories, different vortex-formation modes induced by the wire were revealed. For specific wire positions, decreases of up to 98 % and increases of up to 102 % were identified in the oscillation amplitude of the cylinder compared with the amplitude of the clean cylinder under similar conditions.

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Section: Introductionmentioning

confidence: 89%

Section: Experimental Set-upmentioning

confidence: 99%

Section: Experimental Set-upmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effects of a single spanwise surface wire on a free-ended circular cylinder undergoing vortex-induced vibration in the lower synchronization range

Vaziri

Ekmekci

2022

J. Fluid Mech.

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“…Studies by Ekmekci and Rockwell (2010) at Re=1•10 4 showed that a circular cylinder with a wire with d/D=0.029 positioned before 40 • or after 120 • had relatively little influence on the near-wake structure which concurs well with the present findings. Other studies into the influence of a single span-wise surface wire can be found in Ekmekci and Rockwell (2011) and Aydin et al (2014).…”

Section: Variations In Force Coefficients With Angular Position Of Hementioning

confidence: 99%

Aerodynamics of a stay cable with helical fillets - Part I: Stability and load characteristics

Christiansen

Jakobsen

Macdonald

et al. 2018

Journal of Wind Engineering and Industrial Aerodynamics

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The aerodynamic behaviour of a bridge stay cable with helical fillets in smooth flow at high Reynolds numbers is presented in this paper. The cable response and related sectional load characteristics were studied experimentally on a 1:1 scale cable section model. The studies showed that a cable with helical fillets inclined 60 • to the flow could experience large amplitude wind induced vibrations and that the occurrence of vibrations were highly dependent on cable surface irregularities. The ambition is not to explain fully the excitation mechanism, but to present global and local influences of the helical fillets on the flow field. It was revealed that the flow field around the cable shifted between semi-stable transition states which took place when the transition from laminar to turbulent flow propagated from the free shear layers to the boundary layer. The transitions would form locally and spread along the cable axis. The helical fillet appeared to dominate the local flow structures when located at an angular position between 40-130 • from the stagnation region. In the stagnation and base regions, the surface irregularities appeared to dominate. Furthermore, the helical fillets displaced the mean stagnation line. The application of quasi-steady theory with the measurement data available appeared not to be able to explain the vibrations.

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Numerical investigation of the effects of installing four trip wires with different diameters on the mean and fluctuation velocities and characteristics of the wake around the circular cylinder

Mansouri,

Yadegari,

Bak Khoshnevis

2023

J Braz. Soc. Mech. Sci. Eng.

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Critical effects of a spanwise surface wire on flow past a circular cylinder and the significance of the wire size and Reynolds number

Cited by 9 publications

References 21 publications

Effects of a single spanwise surface wire on a free-ended circular cylinder undergoing vortex-induced vibration in the lower synchronization range

Effects of a single spanwise surface wire on a free-ended circular cylinder undergoing vortex-induced vibration in the lower synchronization range

Aerodynamics of a stay cable with helical fillets - Part I: Stability and load characteristics

Numerical investigation of the effects of installing four trip wires with different diameters on the mean and fluctuation velocities and characteristics of the wake around the circular cylinder

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