Turbulent heat transfer in a tube with prescribed heat flux

1968 ◽  
Vol 11 (6) ◽  
pp. 943-962 ◽  
Author(s):  
Hasegawa Shu ◽  
Fujita Yasunobu
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat

Direct numerical simulation of turbulent heat transfer across a sheared wind-driven gas–liquid interface

2016 ◽  
Vol 804 ◽  
pp. 646-687 ◽  
Author(s):  
Ryoichi Kurose ◽  
Naohisa Takagaki ◽  
Atsushi Kimura ◽  
Satoru Komori
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Mass Transfer ◽  
Heat Flux ◽  
Streamwise Velocity ◽  
Liquid Interface ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Transfer Coefficients ◽  
Turbulent Eddies

Turbulent heat transfer across a sheared wind-driven gas–liquid interface is investigated by means of a direct numerical simulation of gas–liquid two-phase turbulent flows under non-breaking wave conditions. The wind-driven wavy gas–liquid interface is captured using the arbitrary Lagrangian–Eulerian method with boundary-fitted coordinates on moving grids, and the temperature fields on both the gas and liquid sides, and the humidity field on the gas side are solved. The results show that although the distributions of the total, latent, sensible and radiative heat fluxes at the gas–liquid interface exhibit streak features such that low-heat-flux regions correspond to both low-streamwise-velocity regions on the gas side and high-streamwise-velocity regions on the liquid side, the similarity between the heat-flux streak and velocity streak on the gas side is more significant than that on the liquid side. This means that, under the condition of a fully developed wind-driven turbulent field on both the gas and liquid sides, the heat transfer across the sheared wind-driven gas–liquid interface is strongly affected by the turbulent eddies on the gas side, rather than by the turbulent eddies and Langmuir circulations on the liquid side. This trend is quite different from that of the mass transfer (i.e. $\text{CO}_{2}$ gas). This is because the resistance to heat transfer is normally lower than the resistance to mass transfer on the liquid side, and therefore the heat transfer is controlled by the turbulent eddies on the gas side. It is also verified that the predicted total heat, latent heat, sensible heat and enthalpy transfer coefficients agree well with previously measured values in both laboratory and field experiments. To estimate the heat transfer coefficients on both the gas and liquid sides, the surface divergence could be a useful parameter, even when Langmuir circulations exist.

Characterization of Turbulent Heat Transfer in Ribbed Pipe Flow

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Changwoo Kang ◽  
Kyung-Soo Yang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Pipe Flow ◽  
Temperature Fields ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Mean Flow ◽  
Transfer Enhancement ◽  
Pitch Ratio ◽  
The Mean

In the current investigation, we performed large eddy simulation (LES) of turbulent heat transfer in circular ribbed-pipe flow in order to study the effects of periodically mounted square ribs on heat transfer characteristics. The ribs were implemented on a cylindrical coordinate system by using an immersed boundary method, and dynamic subgrid-scale models were used to model Reynolds stresses and turbulent heat flux terms. A constant and uniform wall heat flux was imposed on all the solid boundaries. The Reynolds number (Re) based on the bulk velocity and pipe diameter is 24,000, and Prandtl number is fixed at Pr = 0.71. The blockage ratio (BR) based on the pipe diameter and rib height is fixed with 0.0625, while the pitch ratio based on the rib interval and rib height is varied with 2, 4, 6, 8, 10, and 18. Since the pitch ratio is the key parameter that can change flow topology, we focus on its effects on the characteristics of turbulent heat transfer. Mean flow and temperature fields are presented in the form of streamlines and contours. How the surface roughness, manifested by the wall-mounted ribs, affects the mean streamwise-velocity profile was investigated by comparing the roughness function. Local heat transfer distributions between two neighboring ribs were obtained for the pitch ratios under consideration. The flow structures related to heat transfer enhancement were identified. Friction factors and mean heat transfer enhancement factors were calculated from the mean flow and temperature fields, respectively. Furthermore, the friction and heat-transfer correlations currently available in the literature for turbulent pipe flow with surface roughness were revisited and evaluated with the LES data. A simple Nusselt number correlation is also proposed for turbulent heat transfer in ribbed pipe flow.

Elements of a General Correlation for Turbulent Heat Transfer

1996 ◽  
Vol 118 (2) ◽  
pp. 287-293 ◽  
Author(s):  
P. K. Maciejewski ◽  
A. M. Anderson
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Temperature Rise ◽  
Adiabatic Temperature ◽  
Turbulent Velocity ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Velocity Fluctuations ◽  
Adiabatic Temperature Rise ◽  
General Correlation

Typically, heat transfer researchers present results in the form of an empirically based relationship between a length-based Nusselt number, a length-based Reynolds number, and a fluid Prandtl number. This approach has resulted in a multitude of heat transfer correlations, each tied to a specific geometry type. Two recent studies have contributed key ideas that support the development of a more general correlation for turbulent heat transfer that is based on local parameters. Maciejewski and Moffat (1992a, b) found that wall heat transfer rates scale with streamwise turbulent velocity fluctuations and Anderson and Moffat (1992a, b) found that the adiabatic temperature rise is the driving potential for heat transfer. Using these two concepts and a novel approach to dimensional analysis, the present authors have formulated a general correlation for turbulent heat transfer. This correlation predicts wall heat flux as a function of the turbulent velocity fluctuations, the adiabatic temperature rise, and the fluid properties (density, specific heat, thermal conductivity, and viscosity). The correlation applies to both internal and external flows and is tested in air, water, and FC77. The correlation predicts local values of surface heat flux to within ± 12.0 percent at 95 percent confidence.

An Explicit Algebraic Model for Turbulent Heat Transfer in Wall-Bounded Flow With Streamline Curvature

2006 ◽  
Vol 129 (4) ◽  
pp. 425-433 ◽  
Author(s):  
B. A. Younis ◽  
B. Weigand ◽  
S. Spring
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Flux ◽  
Algebraic Model ◽  
Heat Fluxes ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Streamline Curvature ◽  
Turbulent Heat Fluxes ◽  
The Mean

Fourier’s law, which forms the basis of most engineering prediction methods for the turbulent heat fluxes, is known to fail badly in capturing the effects of streamline curvature on the rate of heat transfer in turbulent shear flows. In this paper, an alternative model, which is both algebraic and explicit in the turbulent heat fluxes and which has been formulated from tensor-representation theory, is presented, and its applicability is extended by incorporating the effects of a wall on the turbulent heat transfer processes in its vicinity. The model’s equations for flows with curvature in the plane of the mean shear are derived and calculations are performed for a heated turbulent boundary layer, which develops over a flat plate before encountering a short region of high convex curvature. The results show that the new model accurately predicts the significant reduction in the wall heat transfer rates wrought by the stabilizing-curvature effects, in sharp contrast to the conventional model predictions, which are shown to seriously underestimate the same effects. Comparisons are also made with results from a complete heat-flux transport model, which involves the solution of differential transport equations for each component of the heat-flux tensor. Downstream of the bend, where the perturbed boundary layer recovers on a flat wall, the comparisons show that the algebraic model yields indistinguishable predictions from those obtained with the differential model in regions where the mean-strain field is in rapid evolution and the turbulence processes are far removed from local equilibrium.

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