Effect of alumina nano-powder on the convection and the entropy generation of water inside an inclined square cavity subjected to a magnetic field: Uniform and non-uniform temperature boundary conditions

2019 ◽  
Vol 152 ◽  
pp. 99-117 ◽  
Author(s):  
Ahmad Hajatzadeh Pordanjani ◽  
Saeed Aghakhani ◽  
Abdulwahab A. Alnaqi ◽  
Masoud Afrand
Keyword(s):  
Magnetic Field ◽  
Boundary Conditions ◽  
Entropy Generation ◽  
Uniform Temperature ◽  
Square Cavity ◽  
Nano Powder ◽  
Temperature Boundary

Thermal performance analysis of hybrid nanofluid natural convection in a square cavity containing an elliptical obstacle under variable magnetic field

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Soufien Belhaj ◽  
Brahim Ben-Beya
Keyword(s):  
Magnetic Field ◽  
Natural Convection ◽  
Boundary Conditions ◽  
Entropy Generation ◽  
Thermal Performance ◽  
Field Variable ◽  
Variable Magnetic Field ◽  
Hybrid Nanofluid ◽  
Square Cavity ◽  
Content Type

Purpose This study aims to analyze entropy generation and magnetohydrodynamic (MHD) natural convection of hybrid nanofluid in a square cavity, with a heated elliptical block placed at the center, in presence of a periodic-variable magnetic field. Design/methodology/approach In this paper, simulations were performed with a FORTRAN home code. The numerical methodology used to solve Navier–Stokes, energy and entropy generation equations with corresponding boundary conditions, is essentially based on the finite volume method and full multigrid acceleration. Findings The cavity is filled with Ag–Tio2/Water hybrid nanofluid. The main objective of this investigation is to predict the effects of body’s size (6 cases), type of applied magnetic field (variable or uniform), the non-dimensional period number of the variable magnetic field (VMF) (0.2 ≤ Λ ≤ 0.8), the inclination angle of the VMF (0 ≤ χ ≤ 90), Rayleigh number (5 × 103 ≤ Ra ≥ 105) and Hartmann number (5 ≤ Ha ≥ 100) on thermal performance, heat transfer rate, entropy generation and flow patterns. Originality/value To the authors’ best knowledge, this paper is the first numerical investigation deals with the entropy generation and natural convection of hybrid nanofluid in a two-dimensional cavity, with specific thermal boundary conditions, containing an elliptical block under periodic-variable magnetic field. Different combinations between flow-governing parameters were made to find optimal thermal performance.

scholarly journals Analysis of the Magnetic Field Effect on Entropy Generation at Thermosolutal Convection in a Square Cavity

Entropy ◽  
2011 ◽  
Vol 13 (5) ◽  
pp. 1034-1054 ◽  
Author(s):  
Mounir Bouabid ◽  
Nejib Hidouri ◽  
Mourad Magherbi ◽  
Ammar Ben Brahim
Keyword(s):  
Magnetic Field ◽  
Entropy Generation ◽  
Field Effect ◽  
Magnetic Field Effect ◽  
Thermosolutal Convection ◽  
Square Cavity ◽  
The Magnetic Field

Effects of Thermal Boundary Conditions on Entropy Generation During Natural Convection in a Differentially Heated Square Cavity

2010 ◽  
Author(s):  
Ram Satish Kaluri ◽  
Tanmay Basak ◽  
A. R. Balakrishnan
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Boundary Conditions ◽  
Entropy Generation ◽  
Bottom Wall ◽  
Convection Flow ◽  
Uniform Heating ◽  
Square Cavity ◽  
Fluid Friction ◽  
Thermal Boundary Conditions

Natural convection is a widely occurring phenomena which has important applications in material processing, energy storage devices, electronic cooling, building ventilation etc. The concept of ‘entropy generation minimization’, which is a thermodynamic approach for optimization, may be very useful in designing efficient thermal systems. In the current study, entropy generation in steady laminar natural convection flow in a square cavity is studied with following isothermal boundary conditions: (1) Bottom wall is uniformly heated (2) Bottom wall is sinusoidally heated. The side walls are maintained cold and the top wall is maintained adiabatic. The thermal boundary condition in non-uniform heating case (case 2) is such that the dimensionless average temperature of the bottom wall is equal to that of uniform heating case (case 1). The prime objective of this work is to investigate the influence of uniform and non-uniform heating on entropy generation. The governing mass, momentum and energy equations are solved using Galerkin finite element method. Streamlines, isotherms, contour maps of entropy generation due to heat transfer and fluid friction are studied for Pr = 0.01 (molten metals) and 7 (water) in range of Ra = 103–105. Detailed analysis on the effect of uniform and non-uniform thermal boundary conditions on entropy generation due to heat transfer and fluid friction has been presented. Also, the average Bejan’s number which indicates the relative dominance of entropy generation due to heat transfer or fluid friction and the total entropy generation are studied for each case.

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 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.

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