A Numerical Study of Three-Dimensional Convective Heat Transfer From a Window Covered by a Simple Partially-Open Plane Blind

2008 ◽  
Author(s):  
Patrick H. Oosthuizen ◽  
Murat Basarir ◽  
David Naylor
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Three Dimensional ◽  
Side Surface ◽  
Governing Equations ◽  
Three Dimensional Flow ◽  
Buoyancy Forces ◽  
Fluid Properties ◽  
Higher Temperature ◽  
Open Plane

Heat transfer from the room-side surface of a window covered by a plane blind to the surrounding room has been considered. The window is at a higher temperature than the air in the room. There is an open gap between the blind system and the window at the top of the window and the effect of the size of this gap on the window-to-air heat transfer rate has been numerically examined. Three-dimensional flow has been considered. The flow has been assumed to be steady and laminar and it has been assumed that the fluid properties are constant except for the density change with temperature which gives rise to the buoyancy forces, this having been treated by using the Boussinesq approach. It has also been assumed that the flow is symmetrical about the vertical centre-plane of the window. The solution has been obtained by numerically solving the full three-dimensional form of the governing equations, these equations being written in terms of dimensionless variables. Results have only been obtained for a Prandtl number of 0.7. The effects of the other dimensionless parameters on the window Nusselt number have been numerically determined.

Eddie Leonardi Memorial Lecture: “Natural Convection From Earth to Space”

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Victoria Timchenko
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Numerical Solutions ◽  
Numerical Study ◽  
Three Dimensional ◽  
Experimental Investigations ◽  
Memorial Lecture ◽  
Numerical Studies ◽  
Fluid Properties ◽  
Microgravity Conditions

This lecture is dedicated to the memory of Professor Eddie Leonardi, formerly International Heat Transfer Conference (IHTC-13) Secretary, who tragically died at an early age on December 14, 2008. Eddie Leonardi had a large range of research interests: he worked in both computational fluid dynamics/heat transfer and refrigeration and air-conditioning for over 25 years. However starting from his Ph.D. ‘A numerical study of the effects of fluid properties on natural convection’ awarded in 1984, one of his main passions has been natural convection and therefore the focus of this lecture will be on what Eddie Leonardi has achieved in numerical and experimental investigations of laminar natural convective flows. A number of examples will be presented which illustrate important difficulties of numerical calculations and experimental comparisons. Eddie Leonardi demonstrated that variable properties have important effects and significant differences occur when different fluids are used, so that dimensionless formulation is not appropriate when dealing with flows of fluids with significant changes in transport properties. Difficulties in comparing numerical solutions with either numerically generated data or experimental results will be discussed with reference to two-dimensional natural convection and three-dimensional Rayleigh–Bénard convection. For a number of years Eddie Leonardi was involved in a joint US-French-Australian research program—the MEPHISTO experiment on crystal growth—and studied the effects of convection on solidification and melting under microgravity conditions. Some results of this research will be described. Finally, some results of experimental and numerical studies of natural convection for building integrated photovoltaic (BIPV) applications in which Eddie Leonardi had been working in the last few years will be also presented.

A NUMERICAL STUDY OF FREE CONVECTIVE HEAT TRANSFER FROM A HEATED HALF-CYLINDER IN AN ENCLOSURE

1995 ◽  
Vol 19 (3) ◽  
pp. 285-300
Author(s):  
P.H. Oosthuizen ◽  
J.T. Paul
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Boussinesq Approximation ◽  
Approximate Model ◽  
Governing Equations ◽  
Free Convective Flow ◽  
Wide Range ◽  
Fluid Properties ◽  
Different Temperatures ◽  
Side Walls

Two-dimensional free convective flow in an enclosure which has a heated half-cylinder on the floor has been numerically studied. The half-cylinder is kept at a uniform high temperature. The enclosure has horizontal upper and lower walls and inclined side-walls. The side-walls are also kept at uniform temperatures and the top and bottom surfaces are adiabatic. In general, the side-walls have been assumed to be at different temperatures. The situation considered is an approximate model of that which occurs in some simple crop dryers. The flow has been assumed to be steady and laminar. Fluid properties have been assumed constant except for the density change with temperature which has been treated using the Boussinesq approximation. The governing equations have been written in dimensionless form and solved using a finite element method. Results have been obtained for a wide range of the governing parameters for a Prandtl number of 0.7, i.e. for air, and the effects of these governing parameters on the heat transfer rate has been studied.

Eddie Leonardi Memorial Lecture: Natural Convection from Earth to Space

2010 ◽  
Author(s):  
Victoria Timchenko
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Numerical Solutions ◽  
Numerical Study ◽  
Three Dimensional ◽  
Experimental Investigations ◽  
Memorial Lecture ◽  
Thermally Driven ◽  
Fluid Properties ◽  
Microgravity Conditions

This lecture is dedicated to the memory of Professor Eddie Leonardi, formerly International Heat Transfer Conference (IHTC-13) Secretary, who tragically died at an early age on December 14, 2008. Eddie Leonardi had a large range of research interests: he worked in both computational fluid dynamics/heat transfer and refrigeration and air-conditioning for over 25 years. However starting from his PhD ‘A numerical Study of the effects of fluid properties on Natural Convection’ awarded in 1984, one of his main passions has been natural convection and therefore the focus of this lecture will be on what Eddie Leonardi has achieved in numerical and experimental investigations of laminar natural convective flows. A number of examples will be presented which illustrate important difficulties of numerical calculations and experimental comparisons. Eddie Leonardi demonstrated that variable properties have important effects and significant differences occur when different fluids are used, so that non-dimensionalisation is not an appropriate tool when dealing with fluids in thermally driven flows in which there are significant changes in transport properties. Difficulties in comparing numerical solutions with either numerically generated data or experimental results will be discussed with reference to two-dimensional natural convection and three-dimensional Rayleigh-Be´nard convection in bounded domains with conducting boundaries. For a number of years Eddie Leonardi was involved in a joint US-French-Australian research program — the MEPHISTO experiment on crystal growth — and studied the effects of convection on solidification and melting under microgravity conditions. The results of this research will be described. Finally, results of experimental and numerical studies of natural convection for Building Integrated Photovoltaic (BIPV) applications in which Eddie Leonardi had been working in the last few years will also be presented.

A Numerical Study of the Effect of Blind Opening on Laminar-to-Turbulent Transition in the Flow Over a Simple Recessed Window-Plane Blind System

2010 ◽  
Author(s):  
Patrick H. Oosthuizen ◽  
David Naylor
Keyword(s):  
Heat Transfer ◽  
Rayleigh Number ◽  
Turbulent Flow ◽  
Numerical Study ◽  
Plane Surface ◽  
Radiant Heat ◽  
Approximate Model ◽  
Radiant Heat Transfer ◽  
Buoyancy Forces ◽  
Open Plane

Most numerical studies of convective heat transfer between a window-blind system and a room are based on the assumption that the flow remains laminar. However, in the case of larger windows it is to be expected that transition to turbulent flow will occur in the system. The aim of the present study was to numerically determine when transition to turbulent flow occurs in a recessed window system and the effect of a simple partially open plane blind on when transition occurs. An approximate model of a recessed window that is covered by a partially open plane blind has been considered. The inner surface of the window is modeled as a plane vertical isothermal surface and the blind as a thin plane surface that offers no resistance to heat transfer. The fluid properties have been assumed constant except for the density change with temperature that gives rise to the buoyancy forces, this being dealt with using the Boussinesq approach. Radiant heat transfer effects have been neglected. The k-epsilon turbulence model with the full effects of the buoyancy forces being accounted for has been used in obtaining the solution. The governing equations have been solved using the commercial finite-volume based cfd code FLUENT. The solution has as parameters: (1) the Rayleigh number, (2) the Prandtl number, (3) the dimensionless ‘window’ recess depth, (4) the dimensionless blind opening, and (5) whether the ‘window’ surface is at a higher or lower temperature than the room air. Because of the application being considered results have only been obtained for Pr = 0.7 and for the case where the ‘window’ surface is at a higher temperature than the room air. The effect of transition on the mean Nusselt number variation with Rayleigh number with various blind openings for various dimensionless window recess depths has in particular been studied.

Numerical Study of Forced Convection in Different Fluids From Stationary Heated Cylinders in a Square Enclosure

2018 ◽  
Author(s):  
Srishti Mishra ◽  
Mukul Tomar ◽  
Adeel Ahmad ◽  
Satvik Jain ◽  
Naveen Kumar
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Transfer Rate ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Flow Characteristics ◽  
Governing Equations ◽  
Square Enclosure ◽  
Nusselt Numbers ◽  
Fluid Properties

This paper performs a numerical study of forced convection heat transfer in a square enclosure with four identical stationary cylinders with single inlet and outlet ports. The ratio of the diameter of the cylinder to the length of the enclosure is kept constant at 0.1 with a fixed spacing between the cylinders. The enclosure walls are adiabatic while the cylinders are maintained at a constant temperature. The governing equations are solved for laminar, steady state and incompressible flow for different fluids namely air, water, and ethylene glycol. The study aims to determine the effect of varying Reynolds number (5 ≤ Re ≤ 100) and fluid properties (0.7 ≤ Pr < 200) on heat transfer rate and flow characteristics. The results of the study are presented in terms of streamlines, isotherm contours, and surface-averaged Nusselt numbers. The 2-D modeling and simulation have been conducted using ANSYS 16.0.

Numerical Study of Heat Transfer in Rectangular Fins for Different Cases of Thermo-Physical Properties

2021 ◽  
Vol 408 ◽  
pp. 83-98
Author(s):  
Imene Bennia ◽  
Tawfik Benabdallah ◽  
Samah Lounis
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Three Dimensional ◽  
Governing Equations ◽  
Unconditionally Stable ◽  
Additional Heat ◽  
Dimensional Simulation ◽  
Volume Method ◽  
Thermo Physical Properties ◽  
Calculation Code

The present work is a contribution to the development of a calculation code that determines the temperature field on fins having rectangular geometry for any bi-dimensional or three-dimensional simulation conditions. Different cases of simulations are presented. An implicit finite volume method, unconditionally stable, is extended in this study for the discretization of the governing equations. The representative results, validated by the Ansys code, show that the fin temperature increases with the increase of the temperature values selected as the boundary conditions, with the addition of a heat flow or any additional heat source. The numerical results are very consistent with the theory and the results obtained from commercialized codes. By increasing the diffusivity one converge more quickly towards the stationary solution. Upon reducing the fin size a very drastic shift occurs from the transient regime to a permanent one. In the case of a refinement of the mesh, the use of a very small epsilon ensures the convergence. Therefore, the results obtained in this study serve as basis of comparison with any other study on heat transfer on rectangular fins.

A Numerical Study on Heat Transfer and Lubricant Depletion on an Anisotropic Multilayer Hard Disk

2012 ◽  
Vol 232 ◽  
pp. 770-774
Author(s):  
Yan Zeng ◽  
Xiao Yang Huang ◽  
Wei Dong Zhou ◽  
Sheng Kai Yu
Keyword(s):  
Heat Transfer ◽  
Laser Power ◽  
Numerical Study ◽  
Disk Surface ◽  
Lubricant Film ◽  
Multilayer Structures ◽  
Lubricant Depletion ◽  
Thermal Anisotropy ◽  
Anisotropy Effect ◽  
Higher Temperature

This paper presents a numerical investigation on the effect of thermal anisotropy of the top layer alloy on heat transfer and lubricant depletion on the disk surface in a heat-assisted magnetic recording (HAMR) system. The disk consists of multilayer structures and a thin layer of lubricant on the top surface. Cases under different laser powers and initial lubricant film thicknesses are examined. The top-layer alloy thermal anisotropy does show non-negligible effect on the heat transfer and lubricant depletion. With the top-layer alloy being more anisotropic, higher temperature increase and lager lubricant depletion can be observed on the disk surface. The results also show that the thermal anisotropy effect is more significant under a lower laser power but nearly keeps no much difference under different initial lubricant film thicknesses. Thus it is of importance to include the thermal anisotropy effect of the top-layer Co-alloy when simulating the heat transfer and lubricant depletion in practical multilayer HMAR systems, especially for the cases under the condition of lower laser power, as the effect cannot be neglected under such conditions.

Numerical Study on the Effect of Inner Tube Position on Heat Transfer Process in Self-Recuperative Radiant Tube

2011 ◽  
Vol 228-229 ◽  
pp. 676-680 ◽  
Author(s):  
Ye Tian ◽  
Xun Liang Liu ◽  
Zhi Wen
Keyword(s):  
Heat Transfer ◽  
Transfer Process ◽  
Numerical Study ◽  
Flame Temperature ◽  
Three Dimensional ◽  
Mathematic Model ◽  
Heat Transfer Process ◽  
Bulk Temperature ◽  
Radiant Tube ◽  
Peak Value

A three-dimensional mathematic model is developed for a 100kw single-end recuperative radiant tube and the simulation is performed with the CFD software FLUENT. Also it is used to investigate the effect of distance between combustion chamber exit and inner tube on heat transfer process. The results suggest that the peak value of combustion flame temperature drops along with the increasing of distance, which leads to low NOX discharging. Also radiant tube surface bulk temperature decreases, which causes radiant tube heating performance losses.

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