Hydrodynamic coefficients of two fixed circular cylinders fitted with helical strakes at various staggered and tandem arrangements

Huang, Shan; Sworn, Andy

doi:10.1016/j.apor.2013.06.001

Cited by 32 publications

(6 citation statements)

References 16 publications

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“…Even through the dynamic responses of the downstream cactus-shaped pipe are less than those of the single circular pipe (compared with Figure 12), the RMS values of both IL and CF micro-strains of the downstream cactus-shaped pipe are generally comparable to those of the downstream circular pipe, which means that the cactus-like body shape modeled in this study does not effectively suppress WIV of the downstream pipe. Other researchers also observe that the mitigation efficiency of helical strakes on the WIV of the downstream pipe is significantly reduced [11]. The reason is that although the cactus-like body shape reduces strength of vortices shed from itself; while, the downstream pipe is mainly excited by the unsteady vortex-structural interaction between itself and the vortices coming from the upstream pipe, thus, the downstream pipe still experiences large oscillations.…”

Section: Water Tunnel Tests On Two Tandem-arranged Flexible Pipesmentioning

confidence: 98%

“…Indeed, WIV of the downstream cylinder is a "wake-excited and wakesustained" flow-induced vibration. Another study conducted by Huang and Sworn [11] on the two fixed cylinders fitted with helical strakes showed that the helical strakes can reduce VIV responses; however, the efficiency of WIV suppression on the downstream cylinder is negatively affected by the wake shed from the upstream cylinder.…”

Section: Introductionmentioning

confidence: 99%

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Mitigation of Vortex-Induced Vibration of Cylinders Using Cactus-Shaped Cross Sections in Subcritical Flow

Wang

Chen

Shi

et al. 2021

JMSE

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Flexible cylinders, such as marine risers, often experience sustained vortex-induced vibrations (VIVs). Installing helical strakes on a riser is the most widely used technique to mitigate VIVs. This study was inspired by the giant Saguaro Cacti which can withstand strong wind with a shallow root system. In this study, numerical simulations of flow past a stationary cylinder of a cactus-shaped cross-section in a two-dimensional flow field at a subcritical Reynolds number of 3900 were performed. Results show that cylinders of a cactus-shaped cross-section have a lower lift coefficient without increasing drag compared to those of a circular cylinder. VIV experiments on a single flexible pipe as well as on a set of two tandem-arranged flexible pipes were conducted at different reduced velocities to investigate the effects of the streamwise spacing and wake of the cactus-like body shape on VIV mitigation. Experimental results show that the cactus-like body shape can mitigate VIV responses of the cylinder at upstream position with no cost of increased drag; however, similar to helical strakes, the efficiency of VIV mitigation for the cylinder at downstream position is reduced. Although the cactus-like body shapes tested in this study were not optimized for oscillation suppression, still this study suggests that modification of the cross-sectional shape to a well-designed cactus-like shape has potentials to be used as an alternative technology to mitigate VIV of marine risers.

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Section: Water Tunnel Tests On Two Tandem-arranged Flexible Pipesmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Mitigation of Vortex-Induced Vibration of Cylinders Using Cactus-Shaped Cross Sections in Subcritical Flow

Wang

Chen

Shi

et al. 2021

JMSE

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“…Fig. 12 (Color online) Flow visualization of the bare and straked cylinder wakes on different planes [132] (4) Helical strakes increase the mean drag coefficient d C [135][136][137] , which is found to be independent of Re [138] and result in a non-zero mean lift coefficient l C [137]. (5) Helical strakes can change the high order harmonics and multi-mode response to a single mode or at least fewer mode response with lower orders [139] .…”

Section: Helical Strakementioning

confidence: 99%

A review on flow-induced vibration of offshore circular cylinders

2020

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As a fundamental fluid-structure interaction (FSI) phenomenon, vortex-induced vibrations (VIVs) of circular cylinders have been the center of the FSI research in the past several decades. Apart from its scientific significance in rich physics, VIVs are paid great attentions by offshore engineers, as they are encountered in many ocean engineering applications. Recently, with the development of research and application, wake-induced vibration (WIV) for multiple cylinders and galloping for VIV suppression attachments are attracting a growing research interest. All these phenomena are connected with the flow-induced vibration (FIV). In this paper, we review and give some discussions on the FIV of offshore circular cylinders, including the research progress on the basic VIV mechanism of an isolated rigid or flexible cylinder, interference of multiple cylinders concerning WIV of multiple cylinders, practical VIV suppression and unwanted galloping for cylinder of attachments. Finally, we draw concluding remarks, give some comments and propose future research prospects, especially on the major challenges as well as potentials in the offline/online modelling and prediction of real-scale offshore structures with high-fidelity CFD methods, new experimental facilities and applications of artificial intelligence tools.

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“…Among these problems, VIV, which can be explained as the vibration stimulated by the external fluid flow vortices when interacting with the structure, is one of the critical design issue of the riser. Currently most of the investigations of the VIV of riser are conducted experimentally [1][2][3][4]. Nevertheless, due to the high cost in constructing the experimental facilities and large aspect ratio of the riser, several factors are usually being constrained in the model testing.…”

Section: Introductionmentioning

confidence: 99%

Prediction of Vortex-Induced Vibration of Bare Cylinder and Cylinder Fitted with Helical Strakes

Lee¹,

Abu²,

Muhamad³

et al. 2017

MATEC Web Conf.

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Abstract. In the study, the vortex-induced vibration (VIV) of a cylinder fitted with and without helical strakes is investigated using fluid-structure interaction (FSI) software. The purpose is to predict the VIV characteristic of cylinder fitted with and without helical strakes. Fluid and structural solvers in commercial computational fluid dynamic (CFD) software were implemented as two-way FSI solvers to develop the simulation. A flexible circular cylinder of diameter, D = 0.018 m was tested. The pitch and height of the helical strakes were 10D and 0.10D, respectively. Existing experiment outputs of bare cylinder were used as benchmark to verify the simulated results. In overall, the simulation was able to predict the trend of the amplitude response and the mean drag coefficient. However, a slight over-prediction was noticed. It was also found that the helical strakes was able to reduce up to 60% of the VIV in water.

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Hydrodynamic coefficients of two fixed circular cylinders fitted with helical strakes at various staggered and tandem arrangements

Cited by 32 publications

References 16 publications

Mitigation of Vortex-Induced Vibration of Cylinders Using Cactus-Shaped Cross Sections in Subcritical Flow

Mitigation of Vortex-Induced Vibration of Cylinders Using Cactus-Shaped Cross Sections in Subcritical Flow

A review on flow-induced vibration of offshore circular cylinders

Prediction of Vortex-Induced Vibration of Bare Cylinder and Cylinder Fitted with Helical Strakes

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