Numerical simulation of the flow around two side-by-side circular cylinders by IVCBC vortex method

Pang, Jianhua; Zong, Zhi; Zou, Li; Wang, Z.

doi:10.1016/j.oceaneng.2016.03.054

Cited by 28 publications

(7 citation statements)

References 21 publications

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“…Yang et al [9] studied the time-averaged pressure distribution and aerodynamic force of the flow around a single cylinder, two cylinders in tandem with different spacings and three cylinders in series by using the wind tunnel test method of rigid model pressure. Pang et al [10] established a numerical calculation model of flow around double cylinders based on instantaneous vorticity conserved boundary conditions based on the characteristics of double cylinders in tandem. Du et al [11] studied the aerodynamic performance and the variation of flow field characteristics of parallel double cylinders with the ratio of cylinder spacing P/D (P refers to the center spacing, and D is the diameter of cylinder) at high Reynolds numbers (Re = 1.4 × 10 5 ) based on the large eddy simulation (LES) method.…”

Section: mentioning

confidence: 99%

Two-dimensional flow field distribution characteristics of flocking drainage pipes in tunnel

et al. 2020

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AbstractWith the rapid development of traffic infrastructure in China, the problem of crystal plugging of tunnel drainage pipes becomes increasingly salient. In order to build a mechanism that is resilient to the crystal plugging of flocking drainage pipes, the present study used the numerical simulation to analyze the two-dimensional flow field distribution characteristics of flocking drainage pipes under different flocking spacings. Then, the results were compared with the laboratory test results. According to the results, the maximum velocity distribution in the flow field of flocking drainage pipes is closely related to the transverse distance h of the fluff, while the longitudinal distance h of the fluff causes little effect; when the transverse distance h of the fluff is less than 6.25D (D refers to the diameter of the fluff), the velocity between the adjacent transverse fluffs will be increased by more than 10%. Moreover, the velocity of the upstream and downstream fluffs will be decreased by 90% compared with that of the inlet; the crystal distribution can be more obvious in the place with larger velocity while it is less at the lower flow rate. The results can provide theoretical support for building a mechanism to deal with and remove the crystallization of flocking drainage pipes.

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Section: mentioning

confidence: 99%

Two-dimensional flow field distribution characteristics of flocking drainage pipes in tunnel

et al. 2020

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“…Chen, Ji, W. Xu, et al, 2015;X. D. Bai et al, 2016;Pang et al, 2016;Singha, Nagarajan, and Sinhamahapatra, 2016), while the last one is herein presented for the first time in the low-Re flow past two side-by-side circular cylinders, being discovered a result of the very small parameter increments. As shown later, the FF flow is further divided into two sub-types, i.e.…”

Section: Wake Behind Side-by-side Circular Cylinders In Laminar Flowmentioning

confidence: 68%

Tianjin Eco-city: A Low-Carbon Model in Singapore–China Cooperation

Gang¹

2015

Singapore–China Relations

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As one of the most intriguing wake patterns of two side-by-side circular cylinders at an intermediate gap spacing, the flip-flopping (FF) flow has attracted great attention of fundamental research interest. This FF flow is featured by the intermittently and randomly switching gap flow together with the alternating increase and decrease of mean drag and fluctuating lift forces of the two cylinders. In the literature, there exists a gap of understanding between the low (laminar) and high (turbulent) Reynolds number FF flows, including the flip-over time interval and opinions on the origin of the flow instability. In this paper, we first present a partition map of the wake patterns behind two side-by-side circular cylinders and briefly introduce intrinsic features of each flow pattern. Then, we focus on the FF flow with an aim to explain three fundamental fluid mechanics principles: (i) the origin of the FF flow between laminar and turbulent regimes, (ii) their connections in different flow regimes, and (iii) mechanisms of the significantly varying flip-over time scale of the FF flows. In the laminar regime, we further divide the FF flow into the sub-classed I (FF1) and II (FF2), based on their different origins from the in-phase and anti-phase synchronized vortex shedding instabilities, respectively. By exploring the vortex interactions, we show that the FF flow in the turbulent regime has the same origin and similar vortex dynamics as the FF2 wake in the laminar regime, in spite of some minor disparities in the vortex merging and pairing. Thus, a connection between the FF2 pattern in the laminar flow and the FF pattern in the turbulent flow is established. It is further found that, for the FF flow in the laminar regime (Re < 150 − 200), the mildly decreasing switching time, being several vortex shedding periods, with the increasing Re arises from the growing vortex strength and shrinking vortex formation length. However, for the FF flow in the weak turbulence regime (150 − 200 < Re < 1000 − 1700), the switching time scale increases significantly with Re owing to the increased vortex formation length, enhanced energy dissipation, and intensified spanwise dislocation. The FF in the strong turbulence regime (Re > 1000 − 1700) has a switching time scale of several orders of magnitude longer than the vortex shedding period, where the switching scale decreases gradually with Re due to the stronger Kelvin-Helmholtz vortices, shorter vortex formation length, and wider turbulent wake.

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“…Instead of the algorithms mentioned above, Pang et al [31,32] have presented instantaneous vorticity conserved boundary conditions (IVCBC) to address elements inside structures using the circle theorem technique [4]. This algorithm ensures that the total circulation of vortex blobs is conserved at any time step, and it can keep the streamlined surface non-destructive.…”

Section: Introductionmentioning

confidence: 99%

Conformal Mapping-Based Discrete Vortex Method for Simulating 2-D Flows around Arbitrary Cylinders

Guo

Sun

Zong

et al. 2021

JMSE

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A novel technique based on conformal mapping and the circle theorem has been developed to tackle the boundary penetration issue, in which vortex blobs leak into structures in two-dimensional discrete vortex simulations, as an alternative to the traditional method in which the blobs crossing the boundary are simply removed from the fluid field or reflected back to their mirror-image positions outside the structure. The present algorithm introduces an identical vortex blob outside the body using the mapping method to avoid circulation loss caused by the vortex blob penetrating the body. This can keep the body surface streamlined and guarantees that the total circulation will be constant at any time step. The model was validated using cases of viscous incompressible flow passing elliptic cylinders with various thickness-to-chord ratios at Reynolds numbers greater than Re = 1 × 105. The force and velocity fields revealed that this boundary scheme converged, and the resultant time-averaged surface pressure distributions were all in excellent agreement with wind tunnel tests. Furthermore, a flow around a symmetrical Joukowski foil at Reynolds number Re = 4.62 × 104, without considering the trailing cusp, was investigated, and a close agreement with the experimental data was obtained.

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Numerical simulation of the flow around two side-by-side circular cylinders by IVCBC vortex method

Cited by 28 publications

References 21 publications

Two-dimensional flow field distribution characteristics of flocking drainage pipes in tunnel

Two-dimensional flow field distribution characteristics of flocking drainage pipes in tunnel

Tianjin Eco-city: A Low-Carbon Model in Singapore–China Cooperation

Conformal Mapping-Based Discrete Vortex Method for Simulating 2-D Flows around Arbitrary Cylinders

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