Periodic Forced Convection in a Darcy Metallic Foam: The LTNE Model

2012 ◽  
Author(s):  
Eugenia Rossi di Schio ◽  
Antonio Barletta
Keyword(s):  
Forced Convection ◽  
Outer Boundary ◽  
Method Of Lines ◽  
Mean Value ◽  
Entrance Region ◽  
Solid Matrix ◽  
Metallic Foam ◽  
The Method Of Lines ◽  
Thermal Entrance Region ◽  
Thermal Entrance

The present paper studies the thermal entrance region in a concentric annular duct filled by a fluid saturated porous metallic foam, with reference to steady forced convection and to a thermal boundary condition given by a wall temperature longitudinally varying with a sinusoidal law. The effect of viscous dissipation in the fluid is taken into account, and a two-temperature model is employed in order to evaluate separately the local fluid and solid matrix temperatures. The governing equations in the thermal entrance region are solved numerically by the method of lines. The Nusselt numer and its mean value in an axial period is evaluated, with reference both to the inner and the outer boundary.

Thermal Nonequilibrium and Viscous Dissipation in the Thermal Entrance Region of a Darcy Flow With Streamwise Periodic Boundary Conditions

2011 ◽  
Vol 133 (7) ◽  
Author(s):  
A. Barletta ◽  
E. Rossi di Schio ◽  
L. Selmi
Keyword(s):  
Viscous Dissipation ◽  
Saturated Porous Medium ◽  
Method Of Lines ◽  
Entrance Region ◽  
Solid Matrix ◽  
The Method Of Lines ◽  
Thermal Entrance Region ◽  
Fluid Saturated Porous Medium ◽  
Thermal Entrance ◽  
Two Temperature

The thermal entrance region in a plane-parallel channel filled by a fluid saturated porous medium is investigated with reference to steady forced convection and to a thermal boundary condition given by a wall temperature longitudinally varying with a sinusoidal law. The effect of viscous dissipation in the fluid is taken into account, and a two-temperature model is employed in order to evaluate separately the local fluid and solid matrix temperatures. The asymptotic temperature distributions are determined analytically. The governing equations in the thermal entrance region are solved numerically by a finite element method and by the method of lines.

Entropy generation analysis for microscale forced convection with radiation in thermal entrance region

2014 ◽  
Vol 51 (3) ◽  
pp. 307-312 ◽  
Author(s):  
Cyrus Aghanajafi ◽  
Maziar Alasvand Bakhtiarpoor ◽  
Mehran Taghipour ◽  
Farid Mohamadi
Keyword(s):  
Forced Convection ◽  
Entropy Generation ◽  
Entrance Region ◽  
Thermal Entrance Region ◽  
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.

Solution for Transient Conjugated Forced Convection in the Thermal Entrance Region of a Duct With Periodically Varying Inlet Temperature

1991 ◽  
Vol 113 (3) ◽  
pp. 558-562 ◽  
Author(s):  
J. S. Travelho ◽  
W. F. N. Santos
Keyword(s):  
Forced Convection ◽  
Entrance Region ◽  
Bulk Temperature ◽  
Inlet Temperature ◽  
Complex Eigenvalue ◽  
Present Solution ◽  
Thermal Entrance Region ◽  
In Series ◽  
Inlet Conditions ◽  
Thermal Entrance

This work presents an analytical solution of the transient conjugated laminar forced convection problem of a slug flow in the thermal entrance region inside a parallel plate duct. A solution in series form is already known for this kind of problem. This solution leads to a complex eigenvalue problem with transcendental equations. The present solution obtained by using the Laplace transform completely eliminates this problem. The amplitudes and phase lags with respect to the inlet conditions are determined for the complex wall temperature, fluid bulk temperature, and wall heat flux from this solution. The results are plotted for comparison with the results obtained with the series solution.

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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