Buoyancy Effects on Laminar Forced Convection in the Thermal Entrance Region of Horizontal Rectangular Channels

1990 ◽  
Vol 112 (1) ◽  
pp. 250-253 ◽  
Author(s):  
F. C. Chou ◽  
G. J. Hwang
Keyword(s):  
Forced Convection ◽  
Entrance Region ◽  
Rectangular Channels ◽  
Thermal Entrance Region ◽  
Laminar Forced Convection ◽  
Thermal Entrance

Effects of Brownian Diffusion and Thermophoresis on the Laminar Forced Convection of a Nanofluid in a Channel

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Eugenia Rossi di Schio ◽  
Michele Celli ◽  
Antonio Barletta
Keyword(s):  
Forced Convection ◽  
Wall Temperature ◽  
Homogeneous Model ◽  
Entrance Region ◽  
Brownian Diffusion ◽  
Boundary Temperature ◽  
Coupled Equations ◽  
Thermal Entrance Region ◽  
Laminar Forced Convection ◽  
Thermal Entrance

A steady laminar forced convection in a parallel–plane channel using nanofluids is studied. The flow is assumed to be fully developed, and described through the Hagen–Poiseuille profile. A boundary temperature varying with the longitudinal coordinate in the thermal entrance region is prescribed. Two sample cases are investigated in detail: a linearly changing wall temperature, and a sinusoidally changing wall temperature. A study of the thermal behavior of the nanofluid is performed by solving numerically the fully–elliptic coupled equations. The numerical solution is obtained by a Galerkin finite element method implemented through the software package Comsol Multiphysics (© Comsol, Inc.). With reference to both the wall temperature distributions prescribed along the thermal entrance region, the governing equations have been solved separately both for the fully developed region and for the thermal entrance region. The analysis shows that if a linearly varying boundary temperature is assumed, for physically interesting values of the Péclet number the concentration field depends very weakly on the temperature distribution. On the other hand, in case of a longitudinally periodic boundary temperature, nonhomogeneities in the nanoparticle concentration distribution arise, which are wrongly neglected whenever the homogeneous model is employed.

Numerical Analysis of Laminar Forced Convection in the Entrance Region of Tubes With Longitudinal Internal Fins

1988 ◽  
Vol 110 (2) ◽  
pp. 310-313 ◽  
Author(s):  
I. M. Rustum ◽  
H. M. Soliman
Keyword(s):  
Forced Convection ◽  
Convection Heat Transfer ◽  
Entrance Region ◽  
Finned Tubes ◽  
Thermal Boundary Conditions ◽  
Thermal Entrance Region ◽  
Internal Fins ◽  
Laminar Forced Convection ◽  
Thermal Entrance ◽  
Steady Laminar

Steady, laminar, forced convection heat transfer in the thermal entrance region of internally finned tubes is investigated numerically for the case of fully developed hydrodynamics using the (H1) and (T) thermal boundary conditions. Results are presented for 16 geometries including the local Nusselt number and developing length corresponding to each boundary condition. These results indicate that internal finning influences the thermal development in a complicated way, which makes it inappropriate to extend the smooth tube results to internally finned tubes on a hydraulic diameter basis.

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