scholarly journals Magnetohydrodynamic mixed convection in a lid-driven rectangular enclosure partially heated at the bottom and cooled at the top

2017 ◽  
Vol 21 (2) ◽  
pp. 863-874 ◽  
Author(s):  
Elif Ogut
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Fluid Flow ◽  
Mixed Convection ◽  
Convection Heat Transfer ◽  
Constant Heat Flux ◽  
Flow Strength ◽  
Moving Wall ◽  
Heater Length ◽  
Heat And Fluid Flow

In the present study, numerical simulation of magnetohydrodynamic (MHD) mixed convection heat transfer and fluid flow has been analyzed in a lid-driven enclosure provided with a constant flux heater. Governing equations were solved via differential quadrature (DQ) method. Moving wall of the enclosure has constant temperature and speed. The calculations were performed for different Richardson number ranging from 0.1 to 10, constant heat flux heater length from 0.2 to 0.8, location of heater center from 0.1 to 0.9, Hartmann number from 0 to 100 and aspect ratio from 0.5 to 2. Two different magnetic field directions were tested as vertical and horizontal. It was found that results of DQ method show good agreement with the results of literature. The magnetic field was more effective when it applied horizontally than that of vertical way. In both direction of magnetic field, it reduced the flow strength and heat transfer. Thus, it can be used as an important control parameter for heat and fluid flow.

Numerical Investigation of Mixed Convection Heat Transfer in Steady Flow Past a Row of Three Square Cylinders

2018 ◽  
Vol 389 ◽  
pp. 164-175
Author(s):  
Houssem Laidoudi ◽  
Bilal Blissag ◽  
Mohamed Bouzit
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Mixed Convection ◽  
Convection Heat Transfer ◽  
Convection Heat ◽  
Thermal Buoyancy ◽  
Flow And Heat Transfer ◽  
Square Cylinders ◽  
Laminar Mixed Convection ◽  
Mixed Convection Heat Transfer

In this paper, the numerical simulations of laminar mixed convection heat transfer from row of three isothermal square cylinders placed in side-by-side arrangement are carried out to understand the behavior of fluid flow around those cylinders under gradual effect of thermal buoyancy and its effect on the evacuation of heat energy. The numerical results are presented and discussed for the range of these conditions: Re = 10 to 40, Ri = 0 to 2 at fixed value of Prandtl number of Pr = 1 and at fixed geometrical configuration. In order to analyze the effect of thermal buoyancy on fluid flow and heat transfer characteristics the main results are illustrated in terms of streamline and isotherm contours. The total drag coefficient as well as average Nusselt number of each cylinder are also computed to determine exactly the effect of buoyancy strength on hydrodynamic force and heat transfer evacuation of each cylinder.

Numerical Study on Fluid Flow and Heat Transfer of Mixed Convection to a Stagnation Region From an Upward-Facing Horizontal Plate

2011 ◽  
Author(s):  
Akihiko Mitsuishi ◽  
Kenzo Kitamura
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Numerical Study ◽  
Infinite Plate ◽  
Convection Heat Transfer ◽  
Constant Heat Flux ◽  
Working Fluid ◽  
Stagnation Region ◽  
Typical Structure ◽  
Recent Experimental Study

Mixed convection heat transfer from an upward-facing horizontal semi-infinite plate to a stagnation region is studied by means of direct numerical simulation. All the cases studied are simulated under constant heat flux condition on the plate. Assuming that the working fluid is air at room temperature and pressure, the Prandtl number is kept at 0.71. The Reynolds and the modified Grashof numbers are in the ranges of 102−103 and 107−108, respectively. Longitudinal vortical structure, which was discovered in the recent experimental study, is successfully simulated. The typical structure appears as a pair of counter-rotating vortices being elongated over the plate. The relationship between this structure and the heat transfer rate is clarified. Characteristics of the vortices are investigated in detail.

scholarly journals Numerical simulation of magneto-hydrodynamics mixed convection in an open channel having a semi-circular heater

2012 ◽  
Vol 9 (2) ◽  
pp. 81-90
Author(s):  
Md. Masum Billah ◽  
M. J. H. Munshi ◽  
A. K. Azad ◽  
M. S. Uddin ◽  
M. M. Rahman
Keyword(s):  
Magnetic Field ◽  
Nusselt Number ◽  
Fluid Flow ◽  
Mixed Convection ◽  
Average Nusselt Number ◽  
Open Channel ◽  
Bottom Surface ◽  
Fluid Temperature ◽  
Rayleigh Numbers ◽  
Heat And Fluid Flow

The present study is conducted to investigate heat and fluid flow in an open channel having a circular heater on the bottom surface under magnetic field. The semi-circle is heated isothermally and the other walls of the channel are kept adiabatic. The consequent mathematical model is governed by the coupled equations of mass, momentum and energy and solved by employing Galerkin weighted residual method of finite-element technique. A wide range of pertinent parameters such as Rayleigh numbers (Ra), and Hartmann numbers (Ha) are considered in the present study. In addition, the mixed convection regime is occurred due to buoyancy and shear forces. Various characteristics such as streamlines, isotherms and heat transfer rate in terms of the average Nusselt number (Nuav), average fluid temperature (?av), and Drag force (D) is investigated for the aforesaid parameters. The magnetic field is found as a control parameter on heat and fluid flow, particularly at higher Rayleigh numbers. It is observed that Hartmann numbers have a significant effect on average Nusselt number, average fluid temperature and Drag force.DOI: http://dx.doi.org/10.3329/jname.v9i2.8020 Journal of Naval Architecture and Marine Engineering 9(2012) 81-90

Combined Effects of Magnetic Field and Thermal Radiation on Fluid Flow and Heat Transfer of Mixed Convection in a Vertical Cylindrical Annulus

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Ben-Wen Li ◽  
Wei Wang ◽  
Jing-Kui Zhang
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Fluid Flow ◽  
Mixed Convection ◽  
Axial Magnetic Field ◽  
Outer Cylinder ◽  
Mhd Equations ◽  
Temperature Fields ◽  
Flow And Heat Transfer ◽  
Cylindrical Annulus

Magnetohydrodynamic (MHD, also for magnetohydrodynamics) mixed convection of electrically conducting and radiative participating fluid is studied in a differentially heated vertical annulus. The outer cylinder is stationary, and the inner cylinder is rotating at a constant angular speed around its axis. The temperature difference between the two cylindrical walls creates buoyancy force, due to the density variation. A constant axial magnetic field is also imposed to resist the fluid motion. The nonlinear integro-differential equation, which characterizes the radiation transfer, is solved by the discrete ordinates method (DOM). The MHD equations, which describe the magnetic and transport phenomena, are solved by the collocation spectral method (CSM). Detailed numerical results of heat transfer rate, velocity, and temperature fields are presented for 0≤Ha≤100, 0.1≤τL≤10, 0≤ω≤1, and 0.2≤εW≤1. The computational results reveal that the fluid flow and heat transfer are effectively suppressed by the magnetic field as expected. Substantial changes occur in flow patterns as well as in isotherms, when the optical thickness and emissivity of the walls vary in the specified ranges. However, the flow structure and the temperature distribution change slightly when the scattering albedo increases from 0 to 0.5, but a substantial change is observed when it increases to 1.

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