scholarly journals Natural Convection and Irreversibility Evaluation in a Cubic Cavity with Partial Opening in Both Top and Bottom Sides

Entropy ◽  
2019 ◽  
Vol 21 (2) ◽  
pp. 116 ◽  
Author(s):  
Hakan Oztop ◽  
Mohammed A. Almeshaal ◽  
Lioua Kolsi ◽  
Mohammed Rashidi ◽  
Mohamed E. Ali
Keyword(s):  
Natural Convection ◽  
Rayleigh Number ◽  
Numerical Study ◽  
Three Dimensional ◽  
Ratio Size ◽  
Partial Opening ◽  
Opening Ratio ◽  
Vertical Walls ◽  
Higher Temperature ◽  
Cubical Cavity

A numerical study on natural convection in a cubical cavity with partial top and bottom openings is performed in this paper. One of the vertical walls of the cavity has higher temperature than that of the opposite one; the remaining walls are insulated perfectly. Three-dimensional simulations of governing equations have been performed using a finite volume technique. The results are presented for different parameters such as opening length and Rayleigh number. It is observed that heat transfer rate and fluid flow can be controlled via opening ratio size and Rayleigh number.

scholarly journals Numerical study of three-dimensional natural convection and entropy generation in a cubical cavity with partially active vertical walls

2017 ◽  
Vol 10 ◽  
pp. 100-110 ◽  
Author(s):  
Abdullah A.A.A Al-Rashed ◽  
Lioua Kolsi ◽  
Ahmed Kadhim Hussein ◽  
Walid Hassen ◽  
Mohamed Aichouni ◽  
...  
Keyword(s):  
Natural Convection ◽  
Entropy Generation ◽  
Numerical Study ◽  
Three Dimensional ◽  
Vertical Walls ◽  
Cubical Cavity

Numerical Study of Three-Dimensional Oscillatory Natural Convection at Low Prandtl Number in Rectangular Enclosures

2000 ◽  
Vol 123 (1) ◽  
pp. 77-83 ◽  
Author(s):  
Shunichi Wakitani
Keyword(s):  
Natural Convection ◽  
Prandtl Number ◽  
Numerical Study ◽  
Three Dimensional ◽  
Width Ratio ◽  
Three Dimensional Flow ◽  
Longitudinal Vortices ◽  
Aspect Ratios ◽  
Vertical Walls ◽  
Prandtl Numbers

Numerical investigations are presented for three-dimensional natural convection at low Prandtl numbers (Pr) from 0 to 0.027 in rectangular enclosures with differentially heated vertical walls. Computations are carried out for the enclosures with aspect ratios (length/height) 2 and 4, and width ratios (width/height) ranging from 0.5 to 4.2. Dependence of the onset of oscillation on the Prandtl number, the aspect ratio, and the width ratio is investigated. Furthermore, oscillatory, three-dimensional flow structure is clarified. The structure is characterized by some longitudinal vortices (rolls) as well as cellular pattern.

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 Numerical Simulation of the Natural Convection with Presence of the Nanofluids in Cubical Cavity

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Mohamed Sannad ◽  
Abourida Btissam ◽  
Belarche Lahoucine
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Volume Fraction ◽  
Numerical Study ◽  
Three Dimensional ◽  
Convection Heat Transfer ◽  
Flow And Heat Transfer ◽  
Heating Section ◽  
The Right

This article consists of a numerical study of natural convection heat transfer in three-dimensional cavity filled with nanofluids. This configuration is heated by a partition maintained at a hot constant and uniform temperature TH. The right and left vertical walls are kept at a cold temperature TC while the rest is adiabatic. The fluid flow and heat transfer in the cavity are studied for different sets of the governing parameters, namely, the nanofluid type, the Rayleigh number Ra = 103, 104, 105, and 106, and the volume fraction Ф varying between Ф = 0 and 0.1. The obtained results show a positive effect of the volume fraction and the Rayleigh number on the heat transfer improvement. The analysis of the results related to the heat transfer shows that the copper-based nanofluid guarantees the best thermal transfer. In addition, the increase of the heating section size and Ra leads to an increased amount of heat. Similarly, increasing the volume fraction improves the intensification of the flow and increases the heat exchange.

Investigation of Natural Convection in Partially Divided Rectangular Enclosures Both With and Without an Opening in the Partition Plate: Measurement Results

1990 ◽  
Vol 112 (3) ◽  
pp. 648-652 ◽  
Author(s):  
K. S. Chen ◽  
A. C. Ku ◽  
C. H. Chou
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Recirculation Zone ◽  
Laser Doppler Velocimeter ◽  
Measurement Results ◽  
Opening Ratio ◽  
Vertical Walls

Experimental results are presented for steady natural convection in a two-dimensional, partially divided, rectangular enclosure, in which two of the vertical walls were maintained at different uniform temperatures and the top and bottom walls were insulated. The partition plate was adiabatic, and the experiment was carried out both with and without an opening in the partition. Rayleigh numbers ranging from 106 to 108 and opening ratios of 0, 1/8, and 1/4 were investigated for an enclosure aspect ratio (length/height) of 2 and Prandtl number of 7 (for water). Local velocity and temperature measurements were made with a laser-Doppler velocimeter and thermocouple probes. Flow visualization using colored dye was also performed. Results show that there was a recirculation zone in the upper and left quadrant of the enclosure when there was no opening in the partition plate. With an opening in the partition, the recirculation zone was absent and the heat transfer rate increased. An unopened partial obstruction would reduce the heat transfer rate by an amount of 12 to 30 percent depending on the Rayleigh number. However, the opening seems to have little effect on the velocity and temperature profiles of the left-moving fluid on the bottom wall. A correlation of the Nusselt number is derived, which shows that the heat transfer rate increases as the Rayleigh number or opening ratio increases.

Numerical Study of Natural Convection in a Partially Open Environment With a Heat Generating Source

2006 ◽  
Author(s):  
Viviana Cocco Mariani ◽  
Adriano da Silva
Keyword(s):  
Natural Convection ◽  
Rayleigh Number ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Vertical Wall ◽  
Internal Heat ◽  
Internal Heating ◽  
Heating Source ◽  
Vertical Walls ◽  
The Difference

A numerical study of the thermal and fluid dynamic behavior of air in a partially open two-dimensional enclosure is presented The enclosure has an opening on the right-hand vertical wall, which is kept at a low given temperature, while the opposite wall has a high given temperature. The natural convection in the enclosure is influenced simultaneously by the difference in temperature between the vertical walls, represented by the Rayleigh number (Rae) and by the internal heating source in the enclosure, represented by the Rayleigh number (Rai). The internal heat source is located on the lower horizontal wall, occupying three different positions. The numerical simulations were executed for 103 ≤ Rae ≤ 106 while the intensity of the two effects - the difference in temperature of the vertical walls and the internal heating source - was evaluated based on the relation R = Rai/Rae, which assumed the values of 400, 1000 and 2500. The results obtained in this study are compared with the results reported in the literature, showing a good congruence.

CFD Analysis of Natural Convection in a Cubic Enclosure Heated From a Side Wall With Experimental Verification Using PIV

2009 ◽  
Author(s):  
Nuri Alpay Ku¨rekci
Keyword(s):  
Natural Convection ◽  
Numerical Study ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Side Wall ◽  
Velocity Measurements ◽  
Dimensional Solution ◽  
Image Velocimetry ◽  
Vertical Walls ◽  
Good Agreement

Natural convection of air in a cubical volume is investigated experimentally and numerically. A cubical volume of 20×20×20 cm dimensions was built for the experimental study. One of the vertical walls covering the volume is hot, the other one is cold and the rest are adiabatic. Three walls are made of aluminum and the others are made of heat-resistant glass. The hot wall temperature is kept constant during the experiments by means of an electrical heater. The cold wall is at the ambient temperature. Other adiabatic surfaces are insulated with polyurethane foam. Experiments are performed in an air-conditioned room at 21°C. PIV (Particle Image Velocimetry) is used for velocity measurements. The FLUENT CFD software package is used for the numerical study. A three-dimensional solution is obtained for the laminar flow case for a 61×61×61 grid. The numerical and experimental results are compared with each other for the validation of the numerical solution under the testing conditions of TH = 69°C, TC = 41°C and Ra = 1.3×107. Results obtained from the numerical and experimental studies are in a reasonably good agreement with each other.

EXPERIMENTAL AND NUMERICAL STUDY OF THREE-DIMENSIONAL NATURAL CONVECTION AND FREEZING IN WATER

1994 ◽  
Author(s):  
C. Abegg ◽  
Graham de Vahl Davis ◽  
W.J. Hiller ◽  
St. Koch ◽  
Tomasz A. Kowalewski ◽  
...  
Keyword(s):  
Natural Convection ◽  
Numerical Study ◽  
Three Dimensional
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