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

scholarly journals Effects of a Rotating Cone on the Mixed Convection in a Double Lid-Driven 3D Porous Trapezoidal Nanofluid Filled Cavity under the Impact of Magnetic Field

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 449 ◽  
Author(s):  
Ali J. Chamkha ◽  
Fatih Selimefendigil ◽  
Hakan F. Oztop
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Nusselt Number ◽  
Aspect Ratio ◽  
Mixed Convection ◽  
Average Nusselt Number ◽  
Volume Fraction ◽  
Rotational Velocity ◽  
Rotating Cone ◽  
The Impact

Effects of a rotating cone in 3D mixed convection of CNT-water nanofluid in a double lid-driven porous trapezoidal cavity is numerically studied considering magnetic field effects. The numerical simulations are performed by using the finite element method. Impacts of Richardson number (between 0.05 and 50), angular rotational velocity of the cone (between −300 and 300), Hartmann number (between 0 and 50), Darcy number (between 10 − 4 and 5 × 10 − 2 ), aspect ratio of the cone (between 0.25 and 2.5), horizontal location of the cone (between 0.35 H and 0.65 H) and solid particle volume fraction (between 0 and 0.004) on the convective heat transfer performance was studied. It was observed that the average Nusselt number rises with higher Richardson numbers for stationary cone while the effect is reverse for when the cone is rotating in clockwise direction at the highest supped. Higher discrepancies between the average Nusselt number is obtained for 2D cylinder and 3D cylinder configuration which is 28.5% at the highest rotational speed. Even though there are very slight variations between the average Nu values for 3D cylinder and 3D cone case, there are significant variations in the local variation of the average Nusselt number. Higher enhancements in the average Nusselt number are achieved with CNT particles even though the magnetic field reduced the convection and the value is 84.3% at the highest strength of magnetic field. Increasing the permeability resulted in higher local and average heat transfer rates for the 3D porous cavity. In this study, the aspect ratio of the cone was found to be an excellent tool for heat transfer enhancement while 95% enhancements in the average Nusselt number were obtained. The horizontal location of the cone was found to have slight effects on the Nusselt number variations.

scholarly journals Effect of Various Tilted Positions of a Thin Fin on Natural Convection of Laminar Viscous Flow in a Square Cavity

2021 ◽  
Vol 39 (5) ◽  
pp. 1634-1642
Author(s):  
Syed Fazuruddin ◽  
Seelam Sreekanth ◽  
G Sankara Sekhar Raju
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Fluid Flow ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Finite Difference ◽  
Average Nusselt Number ◽  
Vertical Position ◽  
Inclination Angles ◽  
Rayleigh Numbers

An exhaustive numerical investigation is carried out to analyze the role of an isothermal heated thin fin on fluid flow and temperature distribution visualization in an enclosure. Natural convection within square enclosures finds remarkable pragmatic applications. In the present study, a finite difference approach is performed on two-dimensional laminar flow inside an enclosure with cold side walls and adiabatic horizontal walls. The fluid flow equations are reconstructed into vorticity - stream function formulation and these equations are employed utilizing the finite-difference strategy with incremental time steps. The parametric study includes a wide scope of Rayleigh number, Ra, and inclination angle ϴ of the thin fin. The effect of different Rayleigh numbers ranging Ra = 104-106 with Pr=0.71 for all the inclination angles from 0°-360° with uniform rotational length of angle 450 of an inclined heated fin on fluid flow and heat transfer have been investigated. The heat transfer rate within the enclosure is measured by means of local and average Nusselt numbers. Regardless of inclination angles of the thin fin, a slight enhancement in the average Nusselt number is observed when Rayleigh number increased for both the cases of the horizontal and vertical position of the thin fin. When the fin has inclined no change in average Nusselt number is noticed for distinct Rayleigh numbers.

scholarly journals Effect of the Presence of a Heat Conducting Horizontal Square Block on Mixed Convection inside a Vented Square Cavity

2009 ◽  
Vol 14 (4) ◽  
pp. 531-548 ◽  
Author(s):  
Md. M. Rahman ◽  
M. A. Alim ◽  
S. Saha ◽  
M. K. Chowdhury
Keyword(s):  
Thermal Conductivity ◽  
Nusselt Number ◽  
Mixed Convection ◽  
Average Nusselt Number ◽  
Working Fluid ◽  
Heat Conducting ◽  
Fluid Temperature ◽  
Square Cavity ◽  
Thermal Fields ◽  
Solid Block

Finite element method is used to solve two-dimensional governing mass, momentum and energy equations for steady state, mixed convection problem inside a vented square cavity. The cavity consists of adiabatic left, top and bottom walls and heated right vertical wall; but it also contains a heat conducting horizontal square block located somewhere inside the cavity. Forced flow conditions are imposed by providing an inlet at the bottom of the left wall and an exit at the top of the right wall, through which the working fluid escape out of the cavity. The aim of the study is to describe the effect of such block on the flow and thermal fields. The investigations are conducted for various values of geometric size, location and thermal conductivity of the block under constant Reynolds and Prandtl numbers. Various results such as the streamlines, isotherms, heat transfer rates in terms of the average Nusselt number, average fluid temperature in the cavity and the temperature at the center of solid block are presented for different parameters. It is observed that the block size and location have significant effect on both the flow and thermal fields but the solid-fluid thermal conductivity ratio has insignificant effect on the flow field. The results also indicate that the average Nusselt number at the heated surface, the average temperature of the fluid inside the cavity and the temperature at the center of solid block are strongly dependent on the configurations of the system studied under different geometrical and physical conditions.

scholarly journals Free convection of a nanofluid in a square cavity with a heat source on the bottom wall and partially cooled from sides

2014 ◽  
Vol 18 (suppl.2) ◽  
pp. 283-300 ◽  
Author(s):  
Mostafa Mahmoodi ◽  
Arani Abbasian ◽  
Sebdani Mazrouei ◽  
Saeed Nazari ◽  
Mohammad Akbari
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Fluid Flow ◽  
Rayleigh Number ◽  
Average Nusselt Number ◽  
Volume Fraction ◽  
Heat Sinks ◽  
Square Cavity ◽  
Flow And Heat Transfer ◽  
Rayleigh Numbers

The problem of free convection fluid flow and heat transfer in a square cavity with a flush mounted heat source on its bottom wall and two heat sinks on its vertical side walls has been investigated numerically. Via changing the location of the heat sinks, six different arrangements have been generated. The cavity was filled with Cu-water nanofluid. The governing equations were discretized using the finite volume method and SIMPLER algorithm. Using the developed code, a parametric study was undertaken, and effects of Rayleigh number, arrangements of the heat sinks and volume fraction of the nanoparticles on fluid flow and heat transfer inside the cavity were investigated. Also for the middle-middle heat sinks arrangement, capability of five different water based nanofluids on enhancement of the rate of heat transfer was examined and compared. From the obtained results it was found that the average Nusselt number, for all six different arrangements of the heat sinks, was an increasing function of the Rayleigh number and the volume fraction of the nanoparticles. Also it was found that at high Rayleigh numbers, maximum and minimum average Nusselt number occurred for middle-middle and top-bottom arrangement, respectively. Moreover it was found that for the middle-middle arrangement, at high Rayleigh numbers, maximum and minimum rate of heat transfer was obtained by Cu-water and TiO2-water nanofluids respectively.

scholarly journals Mixed convection inside nanofluid filled rectangular enclosures with moving bottom wall

2011 ◽  
Vol 15 (3) ◽  
pp. 889-903 ◽  
Author(s):  
Mostafa Mahmoodi
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Fluid Flow ◽  
Mixed Convection ◽  
Richardson Number ◽  
Average Nusselt Number ◽  
Volume Fraction ◽  
Flow And Heat Transfer ◽  
Simpler Algorithm ◽  
Horizontal Wall

The mixed convection fluid flow and heat transfer in lid-driven rectangular enclosures filled with the Al2O3-water nanofluid is investigated numerically. The left and the right vertical walls as well as the top horizontal wall of the enclosure are maintained at a constant cold temperature Tc. The bottom horizontal wall of the enclosure, which moves from left to right, is kept at a constant hot temperature Th, with Th>Tc. The governing equations written in terms of the primitive variables are solved using the finite volume method and the SIMPLER algorithm. Using the developed code, a parametric study is performed and the effects of the Richardson number, the aspect ratio of the enclosure and the volume fraction of the nanoparticles on the fluid flow and heat transfer inside the enclosure are investigated. The results show that at low Richardson numbers, a primary counterclockwise vortex is formed inside the enclosure. More over it is found that for the range of the Richardson number considered, 10-1-101, the average Nusselt number of the hot wall, increases with increasing the volume fraction of the nanoparticles. Also it is observed that the average Nusselt number of the hot wall of tall enclosures is more that to that of the shallow enclosures.

scholarly journals Pulsating Flow of CNT–Water Nanofluid Mixed Convection in a Vented Trapezoidal Cavity with an Inner Conductive T-Shaped Object and Magnetic Field Effects

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 848 ◽  
Author(s):  
Ali J. Chamkha ◽  
Fatih Selimefendigil ◽  
Hakan F. Oztop
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Nusselt Number ◽  
Mixed Convection ◽  
Steady Flow ◽  
Average Nusselt Number ◽  
Pulsating Flow ◽  
Cavity Wall ◽  
Magnetic Field Effects ◽  
Field Effects

Mixed convection of carbon-nanotube/water nanofluid in a vented cavity with an inner conductive T-shaped object was examined under pulsating flow conditions under magnetic field effects with finite element method. Effects of different parameters such as Richardson number (between 0.05 and 50), Hartmann number (between 0 and 30), cavity wall inclination (between 0 ∘ and 10 ∘ ), size (between 0.1 H and 0.4 H) and orientation (between −90 ∘ and 90 ∘ ) of the T-shaped object, and amplitude (between 0.5 and 0.9) and frequency (Strouhal number between 0.25 and 5) of pulsating flow on the convective flow features were studied. It was observed that the average Nusselt number enhanced with the rise of strength of magnetic field, solid nanoparticle volume fraction, and amplitude of the pulsation, while the effect was opposite for higher values of Ri number and cavity wall inclination angle. The presence of the T-shaped object and adjusting its size and orientation had significant impact on the main flow stream from inlet to outlet and recirculations around the T-shaped object and in the vicinity of hot wall of the cavity along with the magnetic field strength. Pulsating flow resulted in heat transfer enhancement as compared to steady flow case for all configurations. However, the amount of increment was different depending on the variation of the parameters of interest. Heat transfer enhancements were 41.85% and 20.81% when the size of the T-shaped object was increased from 0.1 H to 0.4 H. The T-shaped object can be utilized in the vented cavity as an excellent tool for convective heat transfer control. As highly conductive CNT particles were used in water, significant enhancements in the average Nusselt number between 97% and 108% were obtained both in steady flow and in pulsating flow cases when magnetic field was absent or present.

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.

scholarly journals Magnetohydrodynamics Mixed Convection Around a Heat Conducting Horizontal Circular Cylinder in a Rectangular Lid-driven Cavity with Joule Heating

2009 ◽  
Vol 1 (3) ◽  
pp. 461-472 ◽  
Author(s):  
M. M. Rahman ◽  
M. A. Alim ◽  
M. K. Chowdhury
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Mixed Convection ◽  
Richardson Number ◽  
Average Nusselt Number ◽  
Hartmann Number ◽  
Heat Conducting ◽  
Fluid Temperature ◽  
Driven Cavity ◽  
Horizontal Circular Cylinder

In the present paper, a study of magnetohydrodynamic (MHD) mixed convection around a heat conducting horizontal circular cylinder placed at the center of a rectangular cavity along with joule heating has been carried out. Steady state heat transfer by laminar mixed convection has been studied numerically by solving the equations of mass, momentum and energy to determine the fluid flow and heat transfer characteristics in the cavity as a function of Richardson number, Hartmann number and the cavity aspect ratio. The results are presented in the form of average Nusselt number at the heated surface; average fluid temperature in the cavity and temperature at the cylinder center for the range of Richardson number, Hartmann number and aspect ratio. The streamlines and isotherms are also presented. It is found that the streamlines, isotherms, average Nusselt number, average fluid temperature and dimensionless temperature at the cylinder center strongly depend on the Richardson number, Hartmann number and the cavity aspect ratio.Keywords: Mixed convection; Finite element method; Cylinder diameter; Lid-driven cavity; Hartmann number. © 2009 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. DOI: 10.3329/jsr.v1i3.2597               J. Sci. Res. 1 (3), 461-472 (2009) 

scholarly journals Magnetic nanofluid behavior including an immersed rotating conductive cylinder: finite element analysis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hameed K. Hamzah ◽  
Farooq H. Ali ◽  
M. Hatami ◽  
D. Jing ◽  
Mohammed Y. Jabbar
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Nusselt Number ◽  
Average Nusselt Number ◽  
Volume Fraction ◽  
Element Analysis ◽  
Magnetic Nanofluid ◽  
Nusselt Numbers ◽  
Velocity Pressure ◽  
Rayleigh Numbers

AbstractIn this paper, numerical Galerkin Finite Element Method (GFEM) is applied for conjugate heat-transfer of a rotating cylinder immersed in Fe3O4-water nanofluid under the heat-flux and magnetic field. The outer boundaries of the cavity were maintained at low temperatures while beside the cylinder were insulated. It is assumed that the cylinder rotates in both clockwise and counter-clockwise directions. The dimensionless governing equations such as velocity, pressure, and temperature formulation were analyzed by the GFEM. The results were evaluated using the governing parameters such as nanoparticles (NPs) volume fraction, Hartmann and Rayleigh numbers, magnetic field angle and NPs shapes. As a main result, the average Nusselt number increases by increasing the NPs volume fraction, inclination angle and thermal conductivity ratios, while increasing the Hartmann number decreased the Nusselt number. Furthermore, platelet NPs had the maximum average Nusselt number and spherical NPs made the minimum values of Nusselt numbers among examined NPs shapes.

CFD Based Analysis of Laminar Forced Convection of Nanofluid Separated Flow Under the Presence of Magnetic Field

2016 ◽  
Vol 32 (6) ◽  
pp. 777-785
Author(s):  
M. Besanjideh ◽  
M. Hajabdollahi ◽  
S. A. Gandjalikhan Nassab
Keyword(s):  
Magnetic Field ◽  
Fluid Flow ◽  
Volume Fraction ◽  
Separated Flow ◽  
Fluid Temperature ◽  
Flow And Heat Transfer ◽  
Contraction Ratio ◽  
Nanoparticles Volume Fraction ◽  
Energy Equations ◽  
Laminar Forced Convection

AbstractThis paper deals with studying fluid flow and heat transfer of nanofluid through a forward facing step channel which is affected by a uniform magnetic field transverse to fluid flow. All the channel walls are assumed to be in constant temperature and the fluid temperature at the channel inlet is less than that of the walls. Also, the nanofluid is considered as a single-phase Newtonian fluid and the proper correlations were utilized to determine the thermophysical properties of nanofluid. Therefore, a code has been developed and two-dimensional continuity, momentum and energy equations were solved, using CFD technique. The computations were conducted for different values of the Reynolds and Hartmann numbers, and contraction ratio and an extensive range of nanoparticles volume fraction. The results indicated that flow separation and reattachment phenomena, in vicinity of the step edge, could be influenced strongly by magnetic field and the average Nusselt number is increased significantly by increasing nanoparticles volume fraction and Hartmann number.

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