Characteristics of the wake behind a heated cylinder in relatively high Reynolds number

Khashehchi, Morteza; Abdi, Iman Ashtiani; Hooman, Kamel

doi:10.1016/j.ijheatmasstransfer.2015.03.053

Cited by 10 publications

(18 citation statements)

References 22 publications

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“…Flow around a cylindrical object is one of the frequently solved problems; the simple geometry of the cylinder is an interesting physical phenomenon. It concerns various types of structures such as cooling towers, chimneys [3], buildings of circular shape (Figure 1), pylons for cable cars, bridge structures [4][5][6], offshore structures, air-cooled heat exchanges [7], storage tanks, and other industrial buildings [8] and their structural components. More detailed knowledge of the flow field and the effects of wind flow on objects finds its application not only in civil engineering [9], but also in wind engineering [10].…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis of Flow Around a Cylinder in Critical and Subcritical Regime

2021

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Modeling the wind flow around cylindrical buildings is one of the problems within urban physics. Despite the simple geometry of the cylinder, it is an interesting physical phenomenon. Partial knowledge of flow field properties can be found in the literature, but in terms of their use for practical tasks, the data are still incomplete. The authors performed a numerical analysis of the flow around the smooth cylinder in the subcritical and critical regime for Reynolds numbers in the range of Re = 2.3 × 103 to 4 × 105. Turbulent flow was solved using LES model and the numerical solution was compared with available data from experiments or standard. Analysis of the mean stream velocity showed the elongation of the core of the wake with decreasing Re. The pressure coefficient evaluation showed a big difference between its distribution in the subcritical and critical regime. In the subcritical regime, a significant increase in the minimum value and a shift of the extreme close to the axis of the cylinder is proven. The results of the drag coefficient confirm a significant decrease in the transition from subcritical to critical regime, which is indicated in the cited experiments.

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Section: Introductionmentioning

confidence: 99%

Numerical Analysis of Flow Around a Cylinder in Critical and Subcritical Regime

2021

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“…Another broad issue is the study of the effect of a heated circular cylinder on the flow field at different Reynolds numbers, which is solved in [13] or [14]. The wake behind a heated cylinder was experimentally studied in [15]. Not many authors have been concerned with the influence of roughness on flow field characteristics of a heated cylinder [16] and [17].…”

Section: Introductionmentioning

confidence: 99%

Numerical modeling of flow around a heated cylinder with a rough surface

2020

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“…Moreover, other studies on vortex shedding of finned-cylinders show that the vortex shedding frequency is well correlated with the cylinder effective diameter, which is based on the projected frontal area of the cylinder (Mair et al [142], Hamakawa et al [143]). Unlike the aforementioned studies on the detached structures from the wake of finned and bare cylinders, no specific investigation has been conducted in the literature regarding the foamed cylinder type.…”

Section: Introductionmentioning

confidence: 99%

“…Zdravkovich [137] indicated the role of the fins as vortex-spoilers as they disturb the shed vortices, making them less coherent and threedimensional. Moreover, other studies on vortex shedding of finned tubes show that the vortex shedding frequency is well correlated with the tube effective diameter, which is based on the projected frontal area of the tube (Mair et al [142], Hamakawa et al [143] and Ligrani et al [139]). Unlike the mentioned studies on the detached structures from the wake of finned and bare tubes, no specific investigation has been conducted in the literature regarding the foam-wrapped tube type.…”

Section: Introductionmentioning

confidence: 99%

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Wake behind a rough (metal foam-covered) cylinder in cross-flow

Abdi¹

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The flow structures behind a circular cylinder are associated with various instabilities. These instabilities are characterized by the Reynolds number and they include the wake, separated shear layer and boundary layer. Depending on the physical application of the cylinder, increasing the level of turbulence by wrapping the cylinder with metal foam would be a target for drag reduction or heat transfer enhancement.In contrast to the extensive consideration that has been devoted to the flow around bare cylinders, the flow structures around the foam-covered cylinders and the characteristics of the wake behind such surfaces has received relatively little attention. Since the present study explores the possibility of using metal foams as replacements for fins on heat exchanger tubes, investigation on the flow-field structures downstream of a foam-covered cylinder and compare it to the bare cylinder specifies the feasibility of using the foamcovered cylinders in heat exchangers. Moreover, the outcome of this study can be used to develop an appropriate boundary condition for the porous-air interface modelling also increases the knowledge of turbulence in porous media.As it will be discussed more in detail in the following chapters, pressure drop and drag coefficient are directly linked to the wake and recirculation region, and to study these two phenomena, it is necessary to have in depth study on the flow-field down-stream of the cylinder. Hence, the purpose of this study is to investigate the wake region behind a foam- Moreover, using hot-wire anemometry, to investigate the energy of the flow inside and outside of the foam-covered cylinder's wake, let us know if a foam-covered cylinder can be treated as an obstacle to the incident flow with a rough surface or the whole foam can be considered as the combination of local jets that are coming out of the pores and disperse in random directions.III

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Characteristics of the wake behind a heated cylinder in relatively high Reynolds number

Cited by 10 publications

References 22 publications

Numerical Analysis of Flow Around a Cylinder in Critical and Subcritical Regime

Numerical Analysis of Flow Around a Cylinder in Critical and Subcritical Regime

Numerical modeling of flow around a heated cylinder with a rough surface

Wake behind a rough (metal foam-covered) cylinder in cross-flow

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