scholarly journals Effect of Magnetic Field on Mixed Convection Heat Transfer in a Lid-Driven Square Cavity

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
N. A. Bakar ◽  
A. Karimipour ◽  
R. Roslan
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Convection Heat Transfer ◽  
Simple Algorithm ◽  
Square Cavity ◽  
Nusselt Numbers ◽  
Flow And Heat Transfer ◽  
Vertical Walls ◽  
Cold Walls ◽  
Volume Method

The effect of magnetic field on fluid flow and heat transfer in two-dimensional square cavity is analyzed numerically. The vertical walls are insulated; the top wall is maintained at cold temperature, Tc while the bottom wall is maintained at hot temperature, Th where Th>Tc. The dimensionless governing equations are solved using finite volume method and SIMPLE algorithm. The streamlines and isotherm plots and the variation of Nusselt numbers on hot and cold walls are presented.

Natural Convection Cooling of an Array of Flush Mounted Discrete Heaters Inside a 3D Cavity

2017 ◽  
Vol 9 (3) ◽  
pp. 698-721 ◽  
Author(s):  
V. P. M. Senthil Nayaki ◽  
S. Saravanan ◽  
X. D. Niu ◽  
P. Kandaswamy
Keyword(s):  
Heat Transfer ◽  
Aspect Ratio ◽  
Vertical Wall ◽  
Three Dimensional ◽  
Heat Removal ◽  
Simple Algorithm ◽  
Nusselt Numbers ◽  
Flow And Heat Transfer ◽  
Cold Walls ◽  
Volume Method

AbstractAn investigation of natural convective flow and heat transfer inside a three dimensional rectangular cavity containing an array of discrete heat sources is carried out. The array consists of a row and columnwise regular arrangement of identical square shaped isoflux discrete heaters and is flush mounted on a vertical wall of the cavity. A symmetrical isothermal sink condition is maintained by cooling the cavity uniformly from either the opposite wall or the side walls or the top and bottom walls. The other walls of the cavity are maintained adiabatic. A finite volume method based on the SIMPLE algorithm and the power law scheme is used to solve the conservation equations. The parametric study covers the influence of pertinent parameters such as the Rayleigh number, the Prandtl number, side aspect ratio of the cavity and cavity heater ratio. A detailed fluid flow and heat transfer characteristics for the three cases are reported in terms of isothermal and velocity vector plots and Nusselt numbers. In general it is found that the overall heat transfer rate within the cavity for Ra=107 is maximum when the side aspect ratio of the cavity lies between 1.5 and 2. A more complex and peculiar flow pattern is observed in the presence of top and bottom cold walls which in turn introduces hot spots on the adiabatic walls. Their location and size are highly sensitive to the side aspect ratio of the cavity and hence offers more effective ways for passive heat removal.

Periodic Fluid Flow and Heat Transfer in a Square Cavity Due to an Insulated or Isothermal Rotating Cylinder

2009 ◽  
Vol 131 (11) ◽  
Author(s):  
Y.-C. Shih ◽  
J. M. Khodadadi ◽  
K.-H. Weng ◽  
A. Ahmed
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Convection Heat Transfer ◽  
Reynolds Numbers ◽  
Rotating Cylinder ◽  
Flow Fields ◽  
Square Cavity ◽  
Nusselt Numbers ◽  
Flow And Heat Transfer ◽  
Rotating Objects

The periodic state of laminar flow and heat transfer due to an insulated or isothermal rotating cylinder object in a square cavity is investigated computationally. A finite-volume-based computational methodology utilizing primitive variables is used. Various rotating objects (circle, square, and equilateral triangle) with different sizes are placed in the middle of a square cavity. A combination of a fixed computational grid and a sliding mesh was utilized for the square and triangle shapes. For the insulated and isothermal objects, the cavity is maintained as differentially heated and isothermal enclosures, respectively. Natural convection heat transfer is neglected. For a given shape of the object and a constant angular velocity, a range of rotating Reynolds numbers are covered for a Pr=5 fluid. The Reynolds numbers were selected so that the flow fields are not generally affected by the Taylor instabilities (Ta<1750). The periodic flow field, the interaction of the rotating objects with the recirculating vortices at the four corners, and the periodic channeling effect of the traversing vertices are clearly elucidated. The simulations of the dynamic flow fields were confirmed against experimental data obtained by particle image velocimetry. The corresponding thermal fields in relation to the evolving flow patterns and the skewness of the temperature contours in comparison to the conduction-only case were discussed. The skewness is observed to become more marked as the Reynolds number is lowered. Transient variations of the average Nusselt numbers of the respective systems show that for high Re numbers, a quasiperiodic behavior due to the onset of the Taylor instabilities is dominant, whereas for low Re numbers, periodicity of the system is clearly observed. Time-integrated average Nusselt numbers of the insulated and isothermal object systems were correlated with the rotational Reynolds number and shape of the object. For high Re numbers, the performance of the system is independent of the shape of the object. On the other hand, with lowering of the hydraulic diameter (i.e., bigger objects), the triangle and the circle exhibit the highest and lowest heat transfers, respectively. High intensity of the periodic channeling and not its frequency is identified as the cause of the observed enhancement.

Laminar Convection Heat Transfer in Square Channel Fitted Diagonally with 45° V-Discrete Baffles

2014 ◽  
Vol 931-932 ◽  
pp. 1149-1153
Author(s):  
Sombat Tamna ◽  
Rachan Poonperm ◽  
Pongjet Promvonge ◽  
Chinaruk Thianpong
Keyword(s):  
Heat Transfer ◽  
Convection Heat Transfer ◽  
Simple Algorithm ◽  
Constant Heat Flux ◽  
Square Channel ◽  
Flow And Heat Transfer ◽  
Smooth Channel ◽  
Drastic Increase ◽  
Laminar Convection ◽  
Volume Method

This work presents a numerical investigation of laminar periodic flow and heat transfer in a constant heat flux-surfaced square-channel fitted diagonally with 45° V-discrete baffles. The computations are based on the finite volume method, and the SIMPLE algorithm has been implemented. The fluid flow and heat transfer characteristics are presented for Reynolds numbers based on the hydraulic diameter of the channel ranging from 200 to 1,200. Effects of different blockage ratios (BR=b/H), BR in range from 0.05-0.2 with pitch ratio of 1.0 on heat transfer and pressure loss in the channel are studied. It is apparent that vortex flows created by the 45° diagonal V-discrete baffle exist and help to induce impinging flows on wall leading to drastic increase in heat transfer rate over the smooth channel. In addition, the increase in the BR results in the rise of Nusselt number and friction factor values. The computational results reveal that the optimum thermal enhancement factor of the 45° V-discrete baffle is about 2.24 at BR=0.2.

scholarly journals Effect of Straight, Inclined and Curved Fins on Natural Convection and Entropy Generation of a Nanofluid in a Square Cavity Influenced by a Magnetic Field

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1339
Author(s):  
Yacine Khetib ◽  
Ahmad Aziz Alahmadi ◽  
Ali Alzaed ◽  
Hamidreza Azimy ◽  
Mohsen Sharifpur ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Entropy Generation ◽  
Transfer Rate ◽  
Simple Algorithm ◽  
Square Cavity ◽  
Maximum Heat ◽  
Maximum Heat Transfer ◽  
Volume Method

In this paper, the free convective heat transfer of nanofluids in a square cavity is simulated using a numerical method. The angle of the cavity could be changed in the horizontal axis from 0 to 90 degrees. The cavity is exposed under a constant magnetic field. Two opposite walls of the cavity are cold and warm, and the rest of the walls are insulated. On the hot wall, there are two fins with the same wall temperature. The equations were discretized by the finite volume method (FVM) and then solved using the SIMPLE algorithm. Three different fin configurations (straight, inclined and curved) were studied in terms of heat transfer rate and generation of entropy. According to the simulation results, the heat transfer rate was improved by tilting the fins toward the top or bottom of the cavity. At Ra = 105 and Ha = 20, the maximum heat transfer rate was achieved at a cavity inclination of 90° and 45°, respectively, for straight and curved fins. In the horizontal cavity, heat transfer rate could be improved up to 6.4% by tilting the fins and up to 4.9% by warping them. Increasing the Hartmann number from 0 to 40 reduced the Nusselt number and entropy generation by 37.9% and 33.8%, respectively.

scholarly journals Effect of Rayleigh Number on Internal Eccentricity in a Heated Horizontal Elliptical Cylinder to its Coaxial Square Enclosure

2020 ◽  
Vol 25 (3) ◽  
pp. 17-29
Author(s):  
Abdelkrim Bouras ◽  
Djedid Taloub ◽  
Zied Driss
Keyword(s):  
Heat Transfer ◽  
Rayleigh Number ◽  
Outer Cylinder ◽  
Boussinesq Approximation ◽  
Square Enclosure ◽  
Nusselt Numbers ◽  
Flow And Heat Transfer ◽  
Commercial Code ◽  
Volume Method ◽  
Rayleigh Numbers

AbstractThis paper deals with numerical investigation of a natural convective flow in a horizontal annular space between a heated square inner cylinder and a cold elliptical outer cylinder with a Newtonian fluid. Uniform temperatures are imposed along walls of the enclosure. The governing equations of the problem were solved numerically by the commercial code Fluent, based on the finite volume method and the Boussinesq approximation. The effects of Geometry Ratio GR and Rayleigh numbers on fluid flow and heat transfer performance are investigated. The Rayleigh number is varied from 103 to 106. Throughout the study the relevant results are presented in terms of isotherms, and streamlines. From the results, we found that the increase in the Geometry Ratio B leads to an increase of the heat transfer coefficient. The heat transfer rate in the annulus is translated in terms of the average Nusselt numbers along the enclosure’s sides. Tecplot 7 program was used to plot the curves which cleared these relations and isotherms and streamlines which illustrate the behavior of air through the channel and its variation with other parameters. The results for the streamlines, isotherms, local and average Nusselt numbers average Nusselt numbers are compared with previous works and show good agreement.

Nanofluid Treatment in Existence of Magnetic Field Using Non-Darcy Model for Porous Media

2018 ◽  
pp. 456-555
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Finite Element Method ◽  
Porous Media ◽  
Control Volume ◽  
Convection Heat Transfer ◽  
Darcy Number ◽  
Convection Heat ◽  
Darcy Model ◽  
Flow And Heat Transfer

In this chapter, the non-Darcy model is employed for porous media filled with nanofluid. Both natural and forced convection heat transfer can be analyzed with this model. The governing equations in forms of vorticity stream function are derived and then they are solved via control volume-based finite element method (CVFEM). The effect of Darcy number on nanofluid flow and heat transfer is examined.

Heat Transfer Improvement in a Square Duct with Diagonal Inclined Ribs

2014 ◽  
Vol 931-932 ◽  
pp. 1144-1148
Author(s):  
Supattarachai Suwannapan ◽  
Ratsak Poomsalood ◽  
Pongjet Promvonge ◽  
Withada Jedsadaratanachai ◽  
Thitipat Limkul
Keyword(s):  
Heat Transfer ◽  
Friction Factor ◽  
Numerical Study ◽  
Simple Algorithm ◽  
Reynolds Numbers ◽  
Square Duct ◽  
Flow And Heat Transfer ◽  
Pitch Ratio ◽  
Volume Method ◽  
Heat Transfer Improvement

This research presents a numerical study of turbulent periodic flow and heat transfer in threedimensional isothermalfluxed square duct with diagonal inclined rib inserted. The fluid flow and heat transfer characteristics are presented for Reynolds numbers in the range of 4000 to 20,000. The computations based on the finite volume method, and the SIMPLE algorithm has been implemented. Effects of rib pitch ratios (0.5 to 2) at a single blockage ratio of 0.2 and attack angle of 60o on heat transfer and friction factor in the duct are examined and their results of the inclined rib are also compared with those of the smooth duct. It is found that the inclined rib provides higher heat transfer rate and friction factor than the smooth duct for all cases. In addition, the decreasing of the pitch ratio leads to the rise in the Nusselt number and friction factor.

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.

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