Combined free‐and‐forced convection: II. Heat transfer in opposing flow

Brown, C. K.; Gavvin, W. H.

doi:10.1002/cjce.5450430609

Cited by 8 publications

(2 citation statements)

References 8 publications

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“…For instance in the buoyancy-opposed case, the particular mode of mixed convection addressed in this paper, the process of heat transfer is enhanced in spite of the flow near the heated surface being retarded and therefore less effective in terms of its convective capability. Such trends have been reported by numerous investigators, for example, Brown and Gauvin [2], Jackson and Fewster [3], and Easby [4].…”

Section: Introductionsupporting

confidence: 69%

The study of buoyancy influence on mean flow and heat transfer under conditions of mixed convection in annular channels

2004

Heat Trans. Asian Res.

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Laser Doppler anemometry (LDA) measurements are reported on mean flow and turbulence in water as it flows downwards through a long vertical passage of annular cross-section having an inner surface which can be uniformly heated and an outer one which is adiabatic. Under buoyancy-opposed conditions, which can be achieved by heating the core and operating at a reduced mass flow rate, the flow near the inner surface is retarded, turbulent velocity fluctuations and turbulent shear stress are increased and the effectiveness of heat transfer is enhanced. When the influence of buoyancy is very strong, flow reversal occurs near the inner surface. Under such conditions, turbulence is produced very readily and the heat transfer process remains very effective, even when the Reynolds number is reduced to values at which the flow is laminar in the absence of heating. The measurements of turbulence in buoyancyopposed flow made in this study provide direct confirmation of the validity of the ideas currently used to explain the influences of buoyancy on mixed convection in vertical passages.

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Section: Introductionsupporting

confidence: 69%

The study of buoyancy influence on mean flow and heat transfer under conditions of mixed convection in annular channels

2004

Heat Trans. Asian Res.

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“…An early report on this topic was by Martinelli and Boelter [1] in their analytical work, where the mechanism in laminar and turbulent flows was reported to be completely different, this was also established by Petukhov and Polykov [2] and in the review paper of Jackson et al [3]. Many researchers have studied mixed convection experimentally over the last five decades, for example Wilks [4], Eckert and Diagula [5] , Brown and Gauvin [6], Steiner [7], Byrne and Ejiogu [8] , Carr et al [9], Khosla et al [10] , Axcell and Hall [11], Polyakov and Shindin [12] , Jackson et al [3], Vilemas et al [13] , Li and Jackson [14]. The continuous experimental and theoretical studies over the last fifty years have led to a general picture that the flow depends on the magnitude of the free convection 2 relative to the forced element.…”

Section: Introductionmentioning

confidence: 94%

The Investigation of Turbulent Buoyancy-Affected Flows for Cooling Applications

Etaig

Elsharif

2019

MJMIE

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This paper details the Turbulent Flows that Affected with Buoyancy and the calculating of the heat transfer relevant to nuclear reactor in vertical pipe, the main topic when buoyancy effects play a significant role. Implementation of the analytical wall functions is used in when the aim is to reduce the computational cost, since conventional wall functions based on prescribed velocity and temperature profiles failed to predict heat transfer accurately in other than a simple shear at high Reynolds numbers. Thus, this work mainly concerns studying the effect of the buoyancy on heat transfer and turbulent flow applying the analytical wall function since it is based on the analytical solution of simplified Reynolds equations and using a new scaling function, which is used to modify the cell averaged dissipation rate. The approach gives results close to those obtained using AWF with scaling function introduced by Gerasimov. The benefit of using the Analytical wall function is that computational cost are more accurate than conventional wall functions. Many improvements added to the approach during its development have been employed in the present work. It has been successfully applied in natural, mixed and mixed convection flows for four different flow geometries.

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Combined forced and free convective diffusion in vertical semipermeable parallel plate ducts

Ramanadhan

Gill

1969

AIChE Journal

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The effect of natural convection on polarization and flow patterns in liquid phase convective diffusion in a vertical duct with semipermeable membrane walls has been investigated theoretically. It is found that at low flow rates, gravitational fields can play a significant role in distorting the velocity profiles and thereby they affect the transition from laminar to turbulent flow. Natural convection also significantly affects mass transfer rates and therefore the extent of polarization at low flow rates. Results are presented for both momentum and mass transfer in upward and downward flows for different wall Peclet numbers. The hydrodynamic stability of the system also has been investigated and critical values of the buoyancy parameters are reported. Also, these results enable one to estimate when natural convection may create errors in membrane testing systems. The analysis and results are of practical interest in reverse osmosis and other membrane separation processes. The more productive the system, the more likely it will be that buoyancy effects are important.

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Combined free‐and‐forced convection: II. Heat transfer in opposing flow

Cited by 8 publications

References 8 publications

The study of buoyancy influence on mean flow and heat transfer under conditions of mixed convection in annular channels

The study of buoyancy influence on mean flow and heat transfer under conditions of mixed convection in annular channels

The Investigation of Turbulent Buoyancy-Affected Flows for Cooling Applications

Combined forced and free convective diffusion in vertical semipermeable parallel plate ducts

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