scholarly journals Numerical Study of Natural Convection of Biological Nanofluid Flow Prepared from Tea Leaves under the Effect of Magnetic Field

Processes ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1824
Author(s):  
Yacine Khetib ◽  
Ahmad Alahmadi ◽  
Ali Alzaed ◽  
Hussein A. Saleem ◽  
Mohsen Sharifpur ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Numerical Study ◽  
Control Volume ◽  
Simple Algorithm ◽  
Tea Leaves ◽  
Nanofluid Flow ◽  
Horizontal Magnetic Field ◽  
Side Walls ◽  
Strong Convection ◽  
Glycol Solution

The heat transfer of a biological nanofluid (N/F) in a rectangular cavity with two hot triangular blades is examined in this work. The properties used for nanoparticles (N/Ps) are derived from a N/P prepared naturally from tea leaves. Silver N/Ps are distributed in a 50–50 water/ethylene glycol solution. The cavity’s bottom wall is extremely hot, while the upper wall is extremely cold. The side walls are insulated, and the enclosure is surrounded by a horizontal magnetic field (M/F). The equations are solved using the control volume technique and the SIMPLE algorithm. Finally, the Nu is determined by changing the dimensions of the blade, the Rayleigh number (Ra), and the Hartmann number (Ha). Finally, a correlation is expressed for the Nu in the range of parameter changes. The results demonstrate that an increment in the Ra from 103 to 105 enhances the Nu more than 2.5 times in the absence of an M/F. An enhancement in the strength of the M/F, especially at the Ra of 105, leads to a dramatic reduction in the Nu. An increase in the height of the triangular blade intensifies the amount of Nu in weak and strong convection. The enlargement of the base of the triangular blade first enhances and then decreases as the Nu. The addition of 5% silver biological N/Ps to the fluid enhances the Nu by 13.7% in the absence of an M/F for high Ras.

Influence of a horizontal magnetic field on the natural convection of paramagnetic fluid in a cube heated and cooled from two vertical side walls

2008 ◽  
Vol 47 (6) ◽  
pp. 668-679 ◽  
Author(s):  
Tomasz Bednarz ◽  
Elzbieta Fornalik ◽  
Hiroyuki Ozoe ◽  
Janusz S. Szmyd ◽  
John C. Patterson ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Natural Convection ◽  
Horizontal Magnetic Field ◽  
Vertical Side ◽  
Side Walls

Numerical Study of Joint Magnetisztion and Gravitational Convection of Air in a Square Enclosure under Quadrupole Magnetic Field

2011 ◽  
Vol 354-355 ◽  
pp. 190-194
Author(s):  
Chang Wei Jiang ◽  
Er Shi ◽  
Xian Feng Zhu ◽  
Zhen Zhou
Keyword(s):  
Magnetic Field ◽  
Magnetic Force ◽  
Numerical Study ◽  
Simple Algorithm ◽  
Potential Method ◽  
Temperature Fields ◽  
Square Enclosure ◽  
Gravitational Fields ◽  
Nusselt Numbers ◽  
Scalar Magnetic Potential

Numerical computations were carried out for theromagnetic convection of air in a square enclosure under both magnetising and gravitational fields. Scalar magnetic potential method was used to calculate magnetic field. The governing equations in primitive variables were discretized by the finite-volume method and solved by the SIMPLE algorithm. The flow and temperature fields for the air natural convection were presented and the local and mean Nusselt numbers on the walls were calculated and compared. The results show that the magnetic force has significant effect on the flow field and heat transfer in a square enclosure, the average Nusselt number respects the trend of decrease first and then increase when the magnetic force number increases.

Integrated Fluxes in Magneto-Hydrodynamic Mixed Convection in a Cavity Sustained by Conjugate Heat Transfer

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Orkodip Mookherjee ◽  
Shantanu Pramanik
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Heat Flux ◽  
Kinetic Energy ◽  
Mixed Convection ◽  
Conjugate Heat Transfer ◽  
Numerical Study ◽  
Horizontal Magnetic Field ◽  
Flow And Heat Transfer ◽  
Stationary Interface

Abstract A numerical study of magneto-hydrodynamic mixed convection in a cavity has been conducted to investigate the influence of magnetic field on integrated flux of thermal energy, linear momentum, and kinetic energy. Shear force through lid motion establishes the forced convection effect and buoyancy force due to differential heating of the moving lid and the stationary interface ensures the natural convection phenomenon. Additionally, conduction through the solid slab with prescribed temperature at the outer surface attached to the cavity induces conjugate heat transfer. Further, the top and bottom walls throughout the domain are kept insulated and a uniform horizontal magnetic field is applied on the interface toward left. Fluid flow and heat transfer characteristics are examined for a range of Hartmann number (Ha): 0, 10, 50, and 120 at fixed values of Reynolds number, Grashof number, and Prandtl number of 300, 9 × 104 and 0.71, respectively. The result shows that the transport of heat in the near wall regions of the fluid domain is primarily governed by diffusion, whereas advection appears stronger in the central region of the cavity. Increase in magnetic field strength from Ha = 0 to 120 gradually suppresses the recirculating structure of the flow signifying a reduction in advective strength as depicted by the decrease in the value of total integrated heat flux from 25.15×10-3 to 6.0×10-3. The reduction in heat flux, momentum fluxes, and kinetic energy fluxes with increase in magnetic field has been well correlated in the range of 0≤Ha≤120.

scholarly journals A NUMERICAL STUDY ON THE EFFECT OF MAGNETIC HEATING TO CRUDE OIL-NANOFLUID FLOW FOR ENHANCED OIL RECOVERY

2020 ◽  
Vol 82 (2) ◽  
Author(s):  
P. H. Tan ◽  
K. S. Fong ◽  
A. Y. Mohd Yassin ◽  
M. Latheef
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Crude Oil ◽  
Enhanced Oil Recovery ◽  
Oil Recovery ◽  
Numerical Study ◽  
Nonlinear Partial Differential Equations ◽  
Cu Nanoparticles ◽  
Nanofluid Flow ◽  
Magnetic Heating

Magnetic heating of crude oil mixed with nanoparticle for heat transfer mechanism enhancement has received much attention in enhanced oil recovery (EOR). In the present work, the heat transfer of Fe3O4, Al2O3, CuO, Cu nanoparticles mixed in crude oil is theoretically investigated. The mathematical model of magnetic field heating in reservoir is represented by the channel flow of crude oil-nanofluid subjected to a longitudinal spatially varying magnetic field. The viscous incompressible flow is bounded by nonisothermal walls. The coupled nonlinear partial differential equations (PDEs) are solved numerically using an unconditionally stable time integration and finite element method. The numerical results are validated against data available in literature. The physical aspects of the crude oil-nanofluid flow and heat transfer are discussed in terms of several pertinent parameters such as solid nano fraction, skin friction, magnetic, Hartmann and Nusselt numbers. It is found that the enhancement of heat transfer increases with the magnetic number and solid nano fraction while decreases with the increase in Hartmann number. It is shown that, the addition of nanoparticle and increment of magnetic number is effective in the localised heating. In addition, the heat transfer of Fe3O4, Al2O3, CuO, Cu nanoparticles in crude oil mixed are investigated and assessed against each other. It is observed that, the heating mechanism would not be as effective for high electrically conducting nanoparticles. The results also indicate that nanoparticle with high thermal conductivity and low electrical conductivity is preferable in obtaining susceptible thermal heating for the EOR.

A numerical study of a bubble pair rising side by side in external magnetic fields

2021 ◽  
Vol 926 ◽  
Author(s):  
Jie Zhang ◽  
Ming-Jiu Ni
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Lorentz Force ◽  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Transverse Field ◽  
Asymmetric Distribution ◽  
Streamwise Vortices ◽  
Horizontal Magnetic Field

The motion of a pair of bubbles rising side by side under the influence of external magnetic fields is numerically examined. Through solving the fully three-dimensional Navier–Stokes equations, the results reveal that the bubble interactions are rather sensitive to the field direction and strength. At first, we identify that, in a hydrodynamic flow, whether the two bubbles will bounce or coalesce depends on the developments of the counter-rotating streamwise vortices during the collision. In particular, for an originally bouncing bubble pair, a streamwise magnetic field tends to promote their coalescence by weakening the strengths of the standing streamwise vortices, and such a weakening effect is caused by the asymmetric distribution of the Lorentz force in the presence of another bubble such that a torque is induced to offset the original streamwise vortices. Under a horizontal magnetic field, on the other hand, the influences are highly dependent on the angle between the bubble centroid line and the field: a transverse field or a moderate spanwise field always leads the bubble pair to coalescence while a strong spanwise field has the opposite effect. This anisotropic effect comes from the Lorentz force induced flow diffusion along the magnetic field, which not only produces two pairs of streamwise vortices at the bubble rear, but also homogenizes the pressure along the magnetic lines. As the competition between the two mechanisms varies with the magnetic direction and strength, the interaction between the bubble pair also changes. We show that the external magnetic fields control the bubble interaction through reconstructing the vortex structures, and hence the core mechanisms are identified.

scholarly journals NUMERICAL STUDY OF MHD CONVECTIVE NANOFLUID FLOWS WITHIN A CORRUGATED TRAPEZOIDAL ENCLOSURE

2020 ◽  
Author(s):  
Victor Job ◽  
Sreedhara Rao Gunakala ◽  
P.V.S.N. Murthy ◽  
R. Panneer Selvam
Keyword(s):  
Microelectromechanical Systems ◽  
Numerical Study ◽  
Governing Equations ◽  
Nanofluid Flow ◽  
Single Walled Carbon Nanotube ◽  
Engineering And Technology ◽  
Side Walls ◽  
Pressure Projection ◽  
Trapezoidal Enclosure ◽  
Design And Manufacture

We consider the unsteady magnetohydrodynamic (MHD) natural convection flows of alumina (Al2O3)-water and single-walled carbon nanotube (SWCNT)-water nanofluids within a symmetrical corrugated trapezoidal enclosure with the effects of viscous and Joule dissipations. In this study, the corrugated bottom wall is isothermally heated, whereas the top wall is thermally insulated. The temperature of the side walls is fixed at the initial nanofluid temperature within the enclosure. We solve the governing equations for velocity and temperature, along with the corresponding initial and boundary conditions, using the polynomial pressure projection stabilized (PPPS) finite element method. The effects of sidewall inclination angle and Eckert number on nanofluid flow and convective heat transfer within the corrugated enclosure are examined. The results obtained from this study are important in various fields of engineering and technology, such as the design and manufacture of efficient heat exchangers and the cooling of microelectromechanical systems (MEMS) using nanofluids.

Numerical study of biofluid flow over a backward-facing step: The hydro-thermal behavior in the presence of magnetic field effects

2016 ◽  
Vol 231 (4) ◽  
pp. 800-812
Author(s):  
M Mohammadpourfard ◽  
F Ghaderi
Keyword(s):  
Magnetic Field ◽  
Shear Stress ◽  
Magnetic Fields ◽  
Wall Shear Stress ◽  
Thermal Behavior ◽  
Numerical Study ◽  
Control Volume ◽  
Flow Simulation ◽  
Magnetic Field Effects ◽  
Wall Shear

In this paper, the results of adding nanoparticles and applying non-uniform magnetic fields on a biofluid (blood) flow through a two-dimensional horizontal channel with a step are reported. Two magnetic fields with positive and negative gradients were applied. The control volume technique and two-phase mixture model in the numerical approach have been used to illustrate the hydro-thermal behavior of flow. Simulation results reveal that nanoparticles can significantly increase the Nusselt number and wall shear stress. Also, the wall shear stress, Nu, and recirculation length in the presence of a magnetic field with different gradients can be externally controlled. Based on the results, the negative gradient magnetic field increases wall shear stress and Nu in the affected region, unlike the positive gradient.

Porous media to intensify natural convection in rectangular enclosures used in building techniques

2020 ◽  
Vol 31 (04) ◽  
pp. 2050061
Author(s):  
A. Baïri ◽  
A. Martín-Garín ◽  
J. A. Millán-García
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Numerical Study ◽  
Control Volume ◽  
Vertical Wall ◽  
Simple Algorithm ◽  
Constant Heat Flux ◽  
Physical Parameters ◽  
Volume Method

This numerical study quantifies the natural convective heat transfer occurring in an elongated rectangular cavity whose hot vertical wall generates a constant heat flux while the opposite one is kept isothermal at cold temperature. The study shows that when a layer of porous material is affixed to the hot wall, the aerodynamic phenomena are modified and increase the natural convective transfer. Several configurations were processed, obtained by varying the matrix’s thermal conductivity of the layer, the aspect ratio of the cavity and the Rayleigh number in wide ranges. The numerical solution is obtained by means of the control volume method based on the SIMPLE algorithm. A correlation of the Nusselt–Rayleigh type is proposed, allowing determination of the convective heat transfer for any combination of these physical parameters. It can be applied in various engineering fields including passive heating in building which can be improved by the simple and easy-to-implement assembly version discussed here.

scholarly journals Natural convection in a square cavity with partially active vertical walls: Time-periodic boundary condition

2006 ◽  
Vol 2006 ◽  
pp. 1-16 ◽  
Author(s):  
N. Nithyadevi ◽  
P. Kandaswamy ◽  
S. Sivasankaran
Keyword(s):  
Natural Convection ◽  
Numerical Study ◽  
Control Volume ◽  
Active Regions ◽  
Governing Equations ◽  
Square Cavity ◽  
Side Walls ◽  
Vertical Walls ◽  
Volume Method ◽  
Time Periodic

A numerical study of transient natural convection in a square cavity with partly thermally active side walls is introduced. The thermally active regions of the side walls are periodic in time. Top and bottom of the cavity are adiabatic. Nine different positions of the thermally active zones are considered. The governing equations are solved using control volume method with power-law scheme. The results are obtained for various values of amplitude, period, and Grashof numbers ranging from104–106and different thermally active situations. It is found that the average heat transfer increases by increasing amplitude forP=1,5, and decreasing forP=3. The average Nusselt number behaves nonlinearly as a function of period.

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