Heightened Thermal Convection as a Result of Splitting a Square Cavity Diagonally in Half

2005 ◽  
Vol 128 (3) ◽  
pp. 251-258 ◽  
Author(s):  
El Hassan Ridouane ◽  
Antonio Campo
Keyword(s):  
Vertical Wall ◽  
Maximum Error ◽  
Correlation Equation ◽  
Temperature Dependent ◽  
Square Cavity ◽  
Cavity System ◽  
The Mean ◽  
The Right ◽  
Volume Method ◽  
Rayleigh Numbers

This investigation addresses the thermogeometric performance of a two-square cavity system contrasted against a two-isosceles triangular cavity system, with an exactly equal heating segment and comparable cooling segment. When one square cavity is cut diagonally in half, it results in a pair of isosceles triangular cavities. The isosceles triangular cavity on the left is heated from the left vertical wall, the top wall is insulated, and the inclined wall is cold; the so-called HIC triangular cavity. The isosceles triangular cavity on the right is heated from the right vertical wall, the bottom wall is insulated, and the inclined wall is cold; the so-called HCI triangular cavity. It may be speculated that the two-isosceles triangular cavity system may find application in the miniaturization of electronic packaging severely constrained by space and/or weight. The finite volume method, accounting for temperature-dependent thermophysical properties of air, is employed to perform the computational analysis. Representative height-based Rayleigh numbers assume values up to 106 to avoid oscillations that occur at a Rayleigh number between RaH=2×106 and 2.2×106. Numerical results are reported for the velocity field, the temperature field, and the local and the mean convective coefficient along the heated vertical wall. Under a dominant conduction condition for RaH=103, the heat flux across the derived two-isosceles triangular system is 334% higher than its counterpart across the original two-square system. In contrast, for a dominant convection condition for RaH=106, this margin diminishes to 20%, but still constitutes a significant improvement. For the design of two-triangular cavity systems, a NuH correlation equation has been constructed yielding a maximum error of 2% at RaH=104.

scholarly journals Mixed Convection and Entropy Generation of an Ag-Water Nanofluid in an Inclined L-Shaped Channel

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1150 ◽  
Author(s):  
Taher Armaghani ◽  
Muneer Ismael ◽  
Ali Chamkha ◽  
Ioan Pop
Keyword(s):  
Nusselt Number ◽  
Mixed Convection ◽  
Entropy Generation ◽  
Richardson Number ◽  
Volume Fraction ◽  
Governing Equations ◽  
Nanoparticles Volume Fraction ◽  
The Mean ◽  
The Right ◽  
Volume Method

This paper investigates the mixed convection and entropy generation of an Ag-water nanofluid in an L-shaped channel fixed at an inclination angle of 30° to the horizontal axis. An isothermal heat source was positioned in the middle of the right inclined wall of the channel while the other walls were kept adiabatic. The finite volume method was used for solving the problem’s governing equations. The numerical results were obtained for a range of pertinent parameters: Reynolds number, Richardson number, aspect ratio, and the nanoparticles volume fraction. These results were Re = 50–200; Ri = 0.1, 1, 10; AR = 0.5–0.8; and φ = 0.0–0.06, respectively. The results showed that both the Reynolds and the Richardson numbers enhanced the mean Nusselt number and minimized the rate of entropy generation. It was also found that when AR. increased, the mean Nusselt number was enhanced, and the rate of entropy generation decreased. The nanoparticles volume fraction was predicted to contribute to increasing both the mean Nusselt number and the rate of entropy generation.

A Numerical Study of Natural Convection in a Cavity With Two Fins Attached to Its Vertical Walls

2007 ◽  
Author(s):  
G. A. Sheikhzadeh ◽  
M. Pirmohammadi ◽  
M. Ghassemi
Keyword(s):  
Nusselt Number ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Square Cavity ◽  
Vertical Walls ◽  
The Mean ◽  
Energy Equations ◽  
Rayleigh Numbers

Numerical study natural convection heat transfer inside a differentially heated square cavity with adiabatic horizontal walls and vertical isothermal walls is investigated. Two perfectly conductive thin fins are attached to the isothermal walls. To solve the governing differential mass, momentum and energy equations a finite volume code based on Pantenkar’s simpler method is developed and utilized. The results are presented in form of streamlines, isotherms as well as Nusselt number for Rayleigh number ranging from 104 up to 107. It is shown that the mean Nusselt number is affected by the position of the fins and length of the fins as well as the Rayleigh number. It is also observed that maximum Nusselt number occurs about the middle of the enclosure where Lf is grater the 0.5. In addition the Nusselt number stays constant and does not varies with width of the cavity (lf) when Lf is equal to 0.5 and Rayleigh number is equal to 104 and 107 as well as when Lf is equal to 0.6 and low Rayleigh numbers.

scholarly journals Mhd Mixed Convection in Copper-Water Nanofluid Filled Lid-Driven Square Cavity Containing Multiple Adiabatic Obstacles with Discrete Heating

2020 ◽  
Vol 25 (2) ◽  
pp. 57-74
Author(s):  
R.S.R. Gorla ◽  
S. Siddiqa ◽  
A.A. Hasan ◽  
T. Salah ◽  
A.M. Rashad
Keyword(s):  
Heat Source ◽  
Mixed Convection ◽  
Convection Flow ◽  
Square Cavity ◽  
Left Wall ◽  
Simpler Algorithm ◽  
Position Parameter ◽  
The Right ◽  
Volume Method ◽  
Good Agreement

AbstractThe objective of the present work is to investigate the influence of nanoparticles of copper within the base fluid (water) on magneto-hydrodynamic mixed-convection flow in a square cavity with internal generation. A control finite volume method and SIMPLER algorithm are used in the numerical calculations. The geometry is a lid-driven square cavity with four interior square adiabatic obstacles. A uniform heat source is located in a part of the left wall and a part of the right wall of the enclosure is maintained at cooler temperature while the remaining parts of the two walls are thermally insulated. Both the upper and bottom walls of the cavity are considered to be adiabatic. A comparison with previously published works shows a very good agreement. It is observed that the Richardson number, Ri, significantly alters the behavior of streamlines when increased from 0.1 to 100.0. Also, the heat source position parameter, D, significantly changes the pattern of isotherms and its strength shifted when D moves from 0.3 to 0.7.

scholarly journals Transient Numerical Analysis of Free Convection in Cylindrical Enclosure

2020 ◽  
Vol 307 ◽  
pp. 01029
Author(s):  
Mohamed Amine Medebber ◽  
Nourddine Retiel ◽  
belkacem Ould said ◽  
Abderrahmane Aissa ◽  
Mohammed El Ganaoui
Keyword(s):  
Free Convection ◽  
Vertical Wall ◽  
Vertical Cylinder ◽  
Geometrical Parameters ◽  
Uniform Temperature ◽  
Governing Equations ◽  
Simpler Algorithm ◽  
Prandtl Numbers ◽  
Volume Method ◽  
Rayleigh Numbers

A transient two dimensional study of free convection in a vertical cylinder partially annulus is conducted numerically. Uniform temperature is imposed cross a vertical wall, while the top and bottom walls are adiabatic. The governing equations are solved numerically by using a finite volume method. The coupling between the continuity and momentum equations is effected using the SIMPLER algorithm. Solutions have been obtained for Prandtl numbers equal to 7.0, Rayleigh numbers of 103to 106and height ratios 0.5. The influence of physical and geometrical parameters on the isotherms, velocity fields, average Nusselt has been numerically investigated.

Natural Convection Patterns in Right-Angled Triangular Cavities with Heated Vertical Sides and Cooled Hypotenuses

2005 ◽  
Vol 127 (10) ◽  
pp. 1181-1186 ◽  
Author(s):  
El Hassan Ridouane ◽  
Antonio Campo ◽  
Jane Y. Chang
Keyword(s):  
Natural Convection ◽  
Vertical Wall ◽  
Ambient Air ◽  
Correlation Equation ◽  
Apex Angle ◽  
Cross Sectional ◽  
Vertical Walls ◽  
Laminar Natural Convection ◽  
Convection Patterns ◽  
Volume Method

The present investigation deals with the numerical computation of laminar natural convection in a gamma of right-angled triangular cavities filled with air. The vertical walls are heated and the inclined walls are cooled while the upper connecting walls are insulated from the ambient air. The defining apex angle α is located at the lower vertex formed between the vertical and inclined walls. This unique kind of cavity may find application in the miniaturization of electronic packaging severely constrained by space and/or weight. The finite volume method is used to perform the computational analysis encompassing a collection of apex angles α compressed in the interval that extends from 5° to 63°. The height-based Rayleigh number, being unaffected by the apex angle α, ranges from a low 103 to a high 106. Numerical results are reported for the velocity field, the temperature field and the mean convective coefficient along the heated vertical wall. Overall, the matching between the numerically predicted temperatures and the experimental measurements of air at different elevations inside a slim cavity is of ordinary quality. For purposes of engineering design, a Nu¯H correlation equation was constructed and also a figure-of-merit ratio between the Nu¯H and the cross sectional area A of the cavity was proposed.

scholarly journals Numerical investigation of natural convection heat transfer in a symmetrically cooled square cavity with a thin fin on its bottom wall

2014 ◽  
Vol 18 (4) ◽  
pp. 1119-1132 ◽  
Author(s):  
Saeid Jani ◽  
Mostafa Mahmoodi ◽  
Meysam Amini ◽  
Jafar Jam
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Constant Temperature ◽  
Convection Heat Transfer ◽  
Bottom Wall ◽  
Square Cavity ◽  
Remarkable Effect ◽  
Simpler Algorithm ◽  
The Right ◽  
Volume Method

In the present paper, natural convection fluid flow and heat transfer in a square cavity heated from below and cooled from sides and the ceiling with a thin fin attached to its hot bottom wall is investigated numerically. The right and the left walls of the cavity, as well as its horizontal top wall are maintained at a constant temperature Tc, while the bottom wall is kept at a constant temperature Th ,with Th > Tc. The governing equations are solved numerically using the finite volume method and the couple between the velocity and pressure fields is done using the SIMPLER algorithm. A parametric study is performed and the effects of the Rayleigh number and the length of the fin on the flow pattern and heat transfer inside the cavity are investigated. Two competing mechanisms that are responsible for the flow and thermal modifications are observed. One is the resistance effect of the fin due to the friction losses which directly depends on the length of the fin, whereas the other is due to the extra heating of the fluid that is offered by the fin. It is shown that for high Rayleigh numbers, placing a hot fin at the middle of the bottom wall has more remarkable effect on the flow field and heat transfer inside the cavity.

Influence of Non Uniform Boundary Conditions on Laminar Free Convection in Wavy Square Cavity With Partial Partitions

Volume 1 ◽  
2004 ◽  
Author(s):  
A. Sabeur-Bendehina ◽  
M. Aounallah ◽  
L. Adjlout ◽  
O. Imine ◽  
B. Imine
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Numerical Study ◽  
Laminar Regime ◽  
Uniform Temperature ◽  
Square Cavity ◽  
Vertical Walls ◽  
The Mean ◽  
Rayleigh Numbers ◽  
Partial Partitions

In the present work, a numerical study of the effect of non uniform boundary conditions on the heat transfer by natural convection in cavities with partial partitions is investigated for the laminar regime. This problem is solved by using the partial differential equations which are the equation of mass, momentum and energy. The tests were performed for different boundary conditions and different Rayleigh numbers while the Prandtl number was kept constant. Four geometrical configurations were considered namely three and five undulations with increasing and decreasing partition length. The results obtained show that the non uniform temperature in the vertical walls affects the flow and the heat transfer. The mean Nusselt number decreases comparing with the heat transfer in the undulated square cavity without partitions for all non uniform boundary conditions tested.

scholarly journals NUMERICAL STUDIES OF NATURAL CONVECTION IN A SQUARE CAVITY

2006 ◽  
Vol 5 (1) ◽  
pp. 68
Author(s):  
Viviana Cocco Mariani ◽  
Ivan Moura Belo
Keyword(s):  
Boussinesq Approximation ◽  
Square Cavity ◽  
Flow Equations ◽  
Nusselt Numbers ◽  
Numerical Studies ◽  
Numeric Simulation ◽  
Different Temperatures ◽  
Convection Problem ◽  
Volume Method ◽  
Rayleigh Numbers

In the present work a numeric study of thermal and fluid dynamics behavior of natural air convection in a bi-dimensional square cavity is presented, in a laminar flow. The square cavity has two walls heated with different temperatures and two isolated walls, the Boussinesq approximation is used and a constant Prandtl number. The Finite Volume Method is used for the discretization of flow equations. The staggered load of variables is adopted and Power-Law and SIMPLE models are used. The numeric simulation is made up of several Rayleigh numbers, 104 Ra 106, and the results of average Nusselt numbers are compared to values obtained in the literature. Flow and isotherm lines are presented and analyzed. The numerical results presented here in this work agree with the ones available in the literature and can be used by researchers who work in the convection problem numeric simulation area.

Free Convection in an Inclined Square Cavity With Partial Partitions on a Wavy Hot Wall

Volume 1 ◽  
2004 ◽  
Author(s):  
M. Belkadi ◽  
A. Azzi ◽  
O. Imine ◽  
L. Adjlout ◽  
M. Aounallah ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Numerical Study ◽  
Wavy Wall ◽  
Square Cavity ◽  
Inclination Angles ◽  
The Mean ◽  
Rayleigh Numbers ◽  
Partial Partitions ◽  
Wall Geometry

In the present investigation, a numerical study of the effect of the hot wavy wall with partial partitions on free convection in an inclined square cavity, differentially heated, was undertaken. This problem is solved by using the partial differential equations which are the equation of mass, momentum, and energy. The tests were performed for different inclination angles, partition lenghts and Rayleigh numbers while the Prandtl number was kept constant. A configuration with three undulations and three partitions has been tested. The results obtained show that the hot wall geometry with partions affects the heat transfer rate in the cavity. The mean Nusselt number decreases notably compared with the heat transfer in the square undulated cavity without partitions.

scholarly journals Transient Natural Convection in Porous Square Cavity Heated and Cooled on Adjacent Walls

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
M. S. Selamat ◽  
I. Hashim ◽  
M. K. Hasan
Keyword(s):  
Steady State ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Vertical Wall ◽  
Transient State ◽  
Governing Equations ◽  
Square Cavity ◽  
Transient Natural Convection ◽  
Temperature Distributions ◽  
Rayleigh Numbers

Transient natural convection in a square cavity filled with a porous medium is studied numerically. The cavity is assumed heated from one vertical wall and cooled at the top, while the other walls are kept adiabatic. The governing equations are solved numerically by a finite difference method. The effects of Rayleigh number on the initial transient state up to the steady state are investigated for Rayleigh number ranging from 10 to2×102. The evolutions of flow patterns and temperature distributions were presented for Rayleigh numbers,Ra=102and103. It is observed that the time taken to reach the steady state is longer for low Rayleigh number and shorter for high Rayleigh number.

Sign in / Sign up

Export Citation Format

Share Document