Development of turbulent heat transfer over the length of vertical tubes in the presence of mixed air convection

Polyakov, A. F.; Shindin, S. A.

doi:10.1016/0017-9310(88)90087-7

Cited by 51 publications

(19 citation statements)

References 6 publications

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“…He demonstrated that the velocity profiles are flattened in flows with influences of weak and medium buoyancy forces when the flow is partially laminarised, and become M-shape when the buoyancy is very strong and turbulence and heat transfer effectiveness regain their strength. These were further confirmed by Carr, Connor & Buhr (1973) and Polyakov & Shindin (1988), both using air, and Kurganov & Kaptilny (1992) using CO 2 at a supercritical pressure. These later studies also provided measurements of the turbulent shear stress, which reduces first with the increase of buoyancy, reaching a minimum (close to zero) while the flow is said fully laminarised.…”

mentioning

confidence: 48%

“…The production of negative turbulent shear stress stems from the velocity gradient of the M-shaped profile in the core region, which has been observed by various researchers previously (e.g. Polyakov & Shindin 1988;Bae et al 2005). Along with the increase of u z u r , turbulent kinetic energy also increases with increase of the body force.…”

Section: The General Picturementioning

confidence: 59%

“…Their study was however for only one flow condition (and a particular distribution of the body force). Polyakov & Shindin (1988) carried out measurements of velocity and turbulence for a wide range of buoyancy values. A limitation of that work is however that the partially laminarising flow that they chose to study was actually close to be fully laminarised, and as a result, they observed the turbulence becoming more isotropic as the flow is laminarised, which is in contrast to the observations of all other studies.…”

Section: The General Picturementioning

confidence: 99%

“…Some positive turbulent shear stress is also produced close to the wall in connection with the near-wall layer (the outer legs of the M-shaped velocity profile). Simultaneous measurements of the axial and wall-normal turbulence were only made by Polyakov & Shindin (1988) who discussed the anisotropy of the turbulence due to the influence of the buoyancy. They concluded that the axial turbulence is more strongly reduced than wall-normal turbulence causing the anisotropy of the turbulence to reduce.…”

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confidence: 99%

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Laminarisation of flow at low Reynolds number due to streamwise body force

Seddighi

2016

J. Fluid Mech.

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It is well established that when a turbulent flow is subjected to a non-uniform body force, the turbulence may be significantly suppressed in comparison with that of the flow of the same flow rate and hence the flow is said to be laminarised. This is the situation in buoyancy-aided mixed convection when severe heat transfer deterioration may occur. Here we report results of direct numerical simulations of flow with a linear or a step-change profile of body force. In contrast to the conventional view, we show that applying a body force to a turbulent flow while keeping the pressure force unchanged causes little changes to the key characteristics of the turbulence. In particular, the mixing characteristics of the turbulence represented by the turbulent viscosity remain largely unaffected. The so-called flow laminarisation due to a body force is in effect a reduction in the apparent Reynolds number of the flow, based on an apparent friction velocity associated with only the pressure force of the flow (i.e. excluding the contribution of the body force). The new understanding allows the level of the flow 'laminarisation' and when the full laminarisation occurs to be readily predicted. In terms of the near-wall turbulence structure, the numbers of ejections and sweeps are little influenced by the imposition of the body force, whereas the strength of each event may be enhanced if the coverage of the body force extends significantly away from the wall. The streamwise turbulent stress is usually increased in accordance with the observation of more and stronger elongated streaks, but the wall-normal and the circumferential turbulent stresses are largely unchanged.

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mentioning

confidence: 48%

Section: The General Picturementioning

confidence: 59%

Section: The General Picturementioning

confidence: 99%

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confidence: 99%

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Laminarisation of flow at low Reynolds number due to streamwise body force

Seddighi

2016

J. Fluid Mech.

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“…Experimental studies of ascending mixed convection air flows include the works of Steiner [1971], Carr et al [1973], Polyakov and Shindin [1988], Vilemas et al [1992] and Shehata and McEligot [1998]. Results for water flows are reported by Parlatan et al [1996].…”

Section: 2) Review Of Previous Workmentioning

confidence: 99%

Refined Eddy Viscosity Schemes and Large Eddy Simulations for Ascending Mixed Convection Flows

Keshmiri

Addad

Cotton

et al. 2008

International Symposium on Advances in Computational Heat Transfer

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The present work is concerned with the modelling of ascending turbulent ('mixed convection') flow in a vertical heated pipe. All fluid properties are assumed to be constant and buoyancy is accounted for within the Boussinesq approximation. Four Eddy Viscosity Models (EVMs) are examined against experimental and numerical (direct simulation) data. The EVMs embody distinct physical refinements with respect to the parent high-Reynolds-number k-ε model. New Large Eddy Simulations (LES) are also presented. Three different CFD codes have been employed in the study: 'CONVERT', 'Code_Saturne', and 'STAR-CD', which are respectively inhouse, industrial, and commercial packages. In general, forced convection flows are best resolved by the LES computations and Cotton-Ismael turbulence model (Cotton and Ismael [1998]). In mixed convection flows the picture changes and the Launder-Sharma closure [Launder and Sharma, 1974] and 'Manchester f v 2 − ' model [Keshmiri et al., 2008] are in closest agreement with the direct simulation heat transfer data. Under conditions of maximum heat transfer impairment, the mean flow and turbulence profiles are best captured by the Large Eddy Simulations and LS and f v 2 − models. However, no single scheme could be said to be in excellent agreement with the data examined.

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Differential model of turbulence: A numerical study of mixed convection in vertical pipes

Лущик¹,

Yakubenko²

1996

Fluid Dyn

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Development of turbulent heat transfer over the length of vertical tubes in the presence of mixed air convection

Cited by 51 publications

References 6 publications

Laminarisation of flow at low Reynolds number due to streamwise body force

Laminarisation of flow at low Reynolds number due to streamwise body force

Refined Eddy Viscosity Schemes and Large Eddy Simulations for Ascending Mixed Convection Flows

Differential model of turbulence: A numerical study of mixed convection in vertical pipes

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