Finite Element Simulation of Magnetohydrodynamic Mixed Convection in a Double-Lid Driven Enclosure With a Square Heat-Generating Block

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
M. M. Rahman ◽  
M. M. Billah ◽  
N. A. Rahim ◽  
R. Saidur ◽  
M. Hasanuzzaman
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Mixed Convection ◽  
Convection Flow ◽  
Weighted Residuals ◽  
Thermal Fields ◽  
Flow And Heat Transfer ◽  
Element Simulation ◽  
Wide Range ◽  
Element Technique

Magnetohydrodynamic (MHD) mixed-convection flow and heat transfer characteristics inside a square double-lid driven enclosure have been investigated in this study. A heat-generating solid square block is positioned at the centre of the enclosure. Both of its vertical walls are lid-driven and have temperature Tc and uniform velocity V0. In addition, the top and bottom surfaces are kept adiabatic. Discretization of governing equations is achieved using finite element technique based on Galerkin weighted residuals. The computation is carried out for a wide range of pertinent parameters such as Hartmann number, heat-generating parameter, and Richardson number. Numerical results are reported for the effects of aforesaid parameters on the streamline and isotherm contours. In addition, the heat transfer rate in terms of the average Nusselt number and temperature of the fluid as well as block center are presented for the mentioned parametric values. The obtained results show that the flow and thermal fields are influenced by the above-mentioned parameters.

scholarly journals A numerical study of mixed convection in a square cavity with a heat conducting square cylinder at different locations

1970 ◽  
Vol 39 (2) ◽  
pp. 78-85 ◽  
Author(s):  
Md Mustafizur Rahman ◽  
MA Alim ◽  
Sumon Saha ◽  
MK Chowdhury
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Mixed Convection ◽  
Numerical Study ◽  
Convection Flow ◽  
Heat Conducting ◽  
Mixed Convection Flow ◽  
Square Cylinder ◽  
Weighted Residuals ◽  
Laminar Mixed Convection

Numerical simulations are carried out for mixed convection flow in a vented cavity with a heat conducting horizontal square cylinder. A two-dimensional solution for steady laminar mixed convection flow is obtained by using the finite element scheme based on the Galerkin method of weighted residuals for different Richardson numbers varying over the range of 0.0 to 5.0. The study goes further to investigate the effect of the inner cylinder position on the fluid flow and heat transfer in the cavity. The location of the inner cylinder is changed horizontally and vertically along the centerline of the cavity. The effects of both Richardson numbers and cylinder locations on the streamlines, isotherms, average rate of heat transfer from the hot wall, the average temperature of the fluid inside the cavity and the temperature at the cylinder center inside the cavity are investigated. The results indicate that the flow field and temperature distributions inside the cavity are strongly dependent on the Richardson numbers and the position of the inner cylinder. Keywords: Finite element method, square cylinder, vented cavity, mixed convection. doi:10.3329/jme.v39i2.1850 Journal of Mechanical Engineering, Vol. ME39, No. 2, Dec. 2008 78-85

Unsteady mixed convection flow at a three-dimensional stagnation point

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Amin Noor ◽  
Roslinda Nazar ◽  
Kohilavani Naganthran ◽  
Ioan Pop
Keyword(s):  
Heat Transfer ◽  
Differential Equations ◽  
Mixed Convection ◽  
Stagnation Point ◽  
Three Dimensional ◽  
Convection Flow ◽  
Mixed Convection Flow ◽  
Content Type ◽  
Flow And Heat Transfer ◽  
Unsteady Mixed Convection

Purpose This paper aims to probe the problem of an unsteady mixed convection stagnation point flow and heat transfer past a stationary surface in an incompressible viscous fluid numerically. Design/methodology/approach The governing nonlinear partial differential equations are transformed into a system of ordinary differential equations by a similarity transformation, which is then solved numerically by a Runge – Kutta – Fehlberg method with shooting technique and a collocation method, namely, the bvp4c function. Findings The effects of the governing parameters on the fluid flow and heat transfer characteristics are illustrated in tables and figures. It is found that dual (upper and lower branch) solutions exist for both the cases of assisting and opposing flow situations. A stability analysis has also been conducted to determine the physical meaning and stability of the dual solutions. Practical implications This theoretical study is significantly relevant to the applications of the heat exchangers placed in a low-velocity environment and electronic devices cooled by fans. Originality/value The case of suction on unsteady mixed convection flow at a three-dimensional stagnation point has not been studied before; hence, all generated numerical results are claimed to be novel.

Characterisation of Flow and Heat Transfer Regimes in Various Horizontal Ducts Submitted to Mixed Convection

2006 ◽  
Author(s):  
C. Abid ◽  
M. Medale ◽  
F. Koffi ◽  
F. Papini ◽  
A. Benderradji
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Mixed Convection ◽  
Thermal Gradient ◽  
Thermal Instability ◽  
Vertical Gradient ◽  
Working Fluid ◽  
Circular Duct ◽  
Flow And Heat Transfer ◽  
Wide Range

The emphasis of this communication is to make a synthesis of several results we have obtained in various mixed convection configurations. This study has been conducted for circular or rectangular ducts submitted to different ways of heating (vertical or horizontal thermal gradient in the rectangular case and combined vertical and horizontal in the circular case). The bibliography is rather poor for mixed convection in liquids, so the chosen working fluid used here is water. Moreover, a wide range of forced fluid flow and heat flux rates has been considered spreading from laminar to turbulent flow. The characterization of fluid flow and heat transfer regimes is based on temporal recording of temperature measurements obtained in several locations by means of thermocouples or infrared thermography. The analysis of these temperature signals highlights several regimes depending on control parameters. The flow structure in the cases of uniformly heated circular duct and the rectangular one heated from below is constituted of two longitudinal rolls and we notice only one roll in the case of the rectangular duct submitted to the horizontal thermal gradient. For low Reynolds and Rayleigh Numbers, the behavior of all these configurations is stable, however the increasing of these parameters induces thermal instability in the case of circular and rectangular ducts heated from below. That means that the thermal vertical gradient is responsible of the occurring of the thermal instability. This result shows that the horizontal thermal gradient is a stabilizing gradient while the vertical one is a destabilizing one. As this instability enhances heat transfer, it will be very helpful to characterize and to identify the domain where it is occurring in order to prevent or to provoke it depending on the expected performance of the heat exchanger. In this paper, we propose to establish a diagram showing the domain of occurrence of this instability for the various cases cited above and to describe the fluid flow and heat transfer associated to these configurations.

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