scholarly journals CFD-based analysis of entropy generation in turbulent double diffusive natural convection flow in square cavity

2020 ◽  
Vol 330 ◽  
pp. 01023
Author(s):  
Khaled Said ◽  
Ahmed Ouadha ◽  
Amina Sabeur
Keyword(s):  
Natural Convection ◽  
Entropy Generation ◽  
Convection Flow ◽  
Concentration Gradients ◽  
Commercial Code ◽  
Left And Right ◽  
Diffusive Effects ◽  
Laminar And Turbulent Regimes ◽  
Double Diffusive ◽  
Good Agreement

The present study concerns the problem of natural and double diffusive natural convection inside differentially heated cavity filled with a binary mixture composed of air and carbon dioxide (CO2). Temperature and CO2 concentration gradients are imposed on both perpendicular left and right walls. Simulations have been performed using the CFD commercial code ANSYS Fluent by solving continuity, momentum, energy and species diffusion equations. Numerical results obtained have been compared to data from the literature for both natural convection thermosolutal cases under laminar and turbulent regimes. For turbulent runs the RNG k-ε model has been selected. A good agreement has been noted between the different types of data for both cases for Rayleigh number ranging between 103 and 1010 and buoyancy ratio between -5 and +5. Entropy generation rates due to thermal, viscous and diffusive effects have been calculated in post processing for all cases.

Entropy generation optimization for MHD natural convection of a nanofluid in porous media-filled enclosure with active parts and viscous dissipation

2017 ◽  
Vol 27 (2) ◽  
pp. 379-399 ◽  
Author(s):  
M.A. Mansour ◽  
Sameh Elsayed Ahmed ◽  
Ali J. Chamkha
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Viscous Dissipation ◽  
Entropy Generation ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Convection Flow ◽  
Negative Effects ◽  
Content Type ◽  
Volume Method

Purpose This paper aims to investigate the entropy generation due to magnetohydrodynamic natural convection flow and heat transfer in a porous enclosure filled with Cu-water nanofluid in the presence of viscous dissipation effect. The left and right walls of the cavity are thermally insulated. There are heated and cold parts, and these are placed on the bottom and top wall, respectively, whereas the remaining parts are thermally insulated. Design/methodology/approach The finite volume method is used to solve the dimensionless partial differential equations governing the problem. A comparison with previously published woks is presented and is found to be in an excellent agreement. Findings The minimization of entropy generation and local heat transfer according to different values of the governing parameters are presented in details. It is found that the presence of magnetic field has negative effects on the local entropy generation because of heat transfer and the local total entropy generation. Also, the increase in the heated part length leads to a decrease in the local Nusselt number. Originality/value This problem is original, as it has not been considered previously.

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.

scholarly journals Analysis of Natural Convection Flow in a Trapezoidal Cavity Containing a Rectangular Heated Body in Presence of External Oriented Magnetic Field

2018 ◽  
Vol 10 (1) ◽  
pp. 11-23 ◽  
Author(s):  
A. Akter ◽  
S. Parvin
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Natural Convection ◽  
Convection Flow ◽  
Natural Convection Flow ◽  
Flow And Heat Transfer ◽  
Heated Body ◽  
Left And Right ◽  
Laminar Natural Convection ◽  
Rectangular Body

The laminar natural convection flow and heat transfer inside a trapezoidal cavity filled with air and containing a rectangular block is investigated numerically. The left and right walls of the cavity are cold, the top and bottom walls are adiabatic and the rectangular body is heated uniformly. Finite Element Method of Galerkin’s weighted residual scheme is used to solve the transport equations with appropriate boundary conditions. The main objective of this study is to explore the influence of pertinent parameters such as Rayleigh number, Hartmann number and orientation of the magnetic field on the flow and heat transfer performance of the fluid while the Prandtl number is considered fixed. Results indicate that the heat transfer rate is significantly affected by increasing the mentioned parameters.

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