Thermo-magnetohydrodynamic effects on Cu + engine oil/water nanofluid flow in a porous media-filled annular region bounded by two rotating cylinders

2020 ◽  
Vol 234 (12) ◽  
pp. 2360-2375 ◽  
Author(s):  
Abuzar Abid Siddiqui ◽  
Ali J Chamkha
Keyword(s):  
Magnetic Field ◽  
Shear Stress ◽  
Transfer Rate ◽  
Outer Cylinder ◽  
Angular Speed ◽  
Engine Oil ◽  
Annular Region ◽  
Nanofluid Flow ◽  
Thermal Transfer ◽  
Physical Variables

We examine the thermo-magnetohydrodynamic effects on nanofluid flow in a porous circular annular region bounded by two rotating cylinders in the presence of a constant radial magnetic field but variable thermal conductivity. The nanofluid consists of a sample liquid (water/ engine oil) along with suspended copper nanoparticles. This physical problem is formulated and analytical solutions for the governing equations are obtained by using the homotopy analysis method in the form of the physical variables such as, the pressure, fluid speed, temperature, shear stress, heat transfer, and the concentration of nanoparticles. The obtained results are compared with the existing results for the clear fluid and are found in excellent agreement. The effects of the field parameters on these physical variables are studied. It is found that the fluid speed (pressure) increases (decreases) with the Forchheirmer coefficient, porosity, applied magnetic field intensity, and the angular speed of the outer cylinder, but it decreases with the angular speed of the inner cylinder for both liquids. The reverse flow exists if the inner and outer cylinders are rotating in the opposite directions for both the liquids. Furthermore, the thermal transfer rate in the engine oil is lower than that in water. If the annulus region is squeezed, then the fluid speed decays while the pressure rises. The temperature and the thermal transfer rate decay if we march from the inner cylinder to the outer one. The porosity and the angular speed of the outer cylinder enhance the viscous dissipation and shear stress.

Dusty hybrid nanofluid flow over a shrinking sheet with magnetic field effects

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Iskandar Waini ◽  
Anuar Ishak ◽  
Ioan Pop ◽  
Roslinda Nazar
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Transfer Rate ◽  
Temporal Stability ◽  
Dust Particles ◽  
Shrinking Sheet ◽  
Hybrid Nanofluid ◽  
Nanofluid Flow ◽  
Content Type ◽  
The Magnetic Field

Purpose This paper aims to examine the Cu-Al2O3/water hybrid nanofluid flow over a shrinking sheet in the presence of the magnetic field and dust particles. Design/methodology/approach The governing partial differential equations for the two-phase flow of the hybrid nanofluid and the dust particles are reduced to ordinary differential equations using a similarity transformation. Then, these equations are solved using bvp4c in MATLAB software. The bvp4c solver is a finite-difference code that implements the three-stage Lobatto IIIa formula. The numerical results are gained for several values of the physical parameters. The effects of these parameters on the flow and the thermal characteristics of the hybrid nanofluid and the dust particles are analyzed and discussed. Later, the temporal stability analysis is used to determine the stability of the dual solutions obtained as time evolves. Findings The outcome shows that the flow is unlikely to exist unless satisfactory suction strength is imposed on the shrinking sheet. Besides, the heat transfer rate on the shrinking sheet decreases with the increase of . However, the increase in and lead to enhance the heat transfer rate. Two solutions are found, where the domain of the solutions is expanded with the rising of, and. Consequently, the boundary layer separation on the surface is delayed in the presence of these parameters. Implementing the temporal stability analysis, it is found that only one of the solutions is stable as time evolves. Originality/value The dusty fluid problem has been widely studied for the flow over a stretching sheet, but only limited findings can be found for the shrinking counterpart. Therefore, this study considers the problem of the dusty fluid flow over a shrinking sheet containing Cu-Al2O3/water hybrid nanofluid with the effect of the magnetic field. In fact, this is the first study to discover the dual solutions of the dusty hybrid nanofluid flow over a shrinking sheet. Also, further analysis shows that only one of the solutions is stable as time evolves.

scholarly journals Effects of Regional Magnetic Field on Rotating MHD Flow Field of Unity Magnetic Prandtl Number

2012 ◽  
Vol 2012 ◽  
pp. 1-17 ◽  
Author(s):  
Sheng Lun Hung ◽  
Jik Chang Leong
Keyword(s):  
Magnetic Field ◽  
Shear Stress ◽  
External Magnetic Field ◽  
Hartmann Number ◽  
Outer Cylinder ◽  
Mhd Flow ◽  
Moving Cylinder ◽  
Magnetic Field Region ◽  
The Magnetic Field ◽  
Region Splitting

This work numerically studies the flow pattern of a magnetic fluid filled within an annulus whose inner cylinder is moving at a constant rotational speed, while the outer cylinder is stationary but under the influence of a nonuniform external magnetic field. The magnetic field consists of four basic configurations, that is, completely circular, semicircular, quarter circular, and alternately quarter circular. The strength of the external magnetic field is characterized using a reference Hartmann number. As the reference Hartmann number increases, the fluid elements need to overcome greater resistance to enter the region with magnetic field. Hence, there always exists an apparent recirculation cell within the region without externally applied magnetic field. The strength and size of the recirculation cell depend on the reference Hartmann number, the number and size of the discrete regions without external magnetic field. Only the shear stress on the moving cylinder always increases in magnitude with the reference Hartmann number and the span of the single external magnetic field region. Splitting and separating the external magnetic field may increase the magnitude of the shear stress on the moving inner cylinder but decrease that on the stationary outer cylinder. If the magnitude of the shear stress on the outer cylinder reduces beyond zero, a shear stress in the opposite sense will increase in magnitude with Hartmann number.

The influence of magnetic field on wall shear stress in power law fluid flow of blood

2021 ◽  
Author(s):  
Amira Husni Talib ◽  
Ilyani Abdullah ◽  
Nik Nabilah Nik Mohd Naser
Keyword(s):  
Magnetic Field ◽  
Shear Stress ◽  
Fluid Flow ◽  
Wall Shear Stress ◽  
Power Law ◽  
Power Law Fluid ◽  
Wall Shear

Effects of uniform or non-uniform heating at bottom wall on MHD mixed convection in a porous cavity saturated by nanofluid

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Subramanian Muthukumar ◽  
Selvaraj Sureshkumar ◽  
Arthanari Malleswaran ◽  
Murugan Muthtamilselvan ◽  
Eswari Prem
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Transfer Rate ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Darcy Number ◽  
Bottom Wall ◽  
Uniform Heating ◽  
The Magnetic Field

Abstract A numerical investigation on the effects of uniform and non-uniform heating of bottom wall on mixed convective heat transfer in a square porous chamber filled with nanofluid in the appearance of magnetic field is carried out. Uniform or sinusoidal heat source is fixed at the bottom wall. The top wall moves in either positive or negative direction with a constant cold temperature. The vertical sidewalls are thermally insulated. The finite volume approach based on SIMPLE algorithm is followed for solving the governing equations. The different parameters connected with this study are Richardson number (0.01 ≤ Ri ≤ 100), Darcy number (10−4 ≤ Da ≤ 10−1), Hartmann number (0 ≤ Ha ≤ 70), and the solid volume fraction (0.00 ≤ χ ≤ 0.06). The results are presented graphically in the form of isotherms, streamlines, mid-plane velocities, and Nusselt numbers for the various combinations of the considered parameters. It is observed that the overall heat transfer rate is low at Ri = 100 in the positive direction of lid movement, whereas it is low at Ri = 1 in the negative direction. The average Nusselt number is lowered on growing Hartmann number for all considered moving directions of top wall with non-uniform heating. The low permeability, Da = 10−4 keeps the flow pattern same dominating the magnetic field, whereas magnetic field strongly affects the flow pattern dominating the high Darcy number Da = 10−1. The heat transfer rate increases on enhancing the solid volume fraction regardless of the magnetic field.

scholarly journals Nanofluid Flow on a Shrinking Cylinder with Al2O3 Nanoparticles

Mathematics ◽  
2021 ◽  
Vol 9 (14) ◽  
pp. 1612
Author(s):  
Iskandar Waini ◽  
Anuar Ishak ◽  
Ioan Pop
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Friction Factor ◽  
Surface Heat Flux ◽  
Transfer Rate ◽  
Surface Heat ◽  
Al2o3 Nanoparticles ◽  
Nanofluid Flow ◽  
Curvature Parameter ◽  
Over Time

This study investigates the nanofluid flow towards a shrinking cylinder consisting of Al2O3 nanoparticles. Here, the flow is subjected to prescribed surface heat flux. The similarity variables are employed to gain the similarity equations. These equations are solved via the bvp4c solver. From the findings, a unique solution is found for the shrinking strength λ≥−1. Meanwhile, the dual solutions are observed when λc<λ<−1. Furthermore, the friction factor Rex1/2Cf and the heat transfer rate Rex−1/2Nux increase with the rise of Al2O3 nanoparticles φ and the curvature parameter γ. Quantitatively, the rates of heat transfer Rex−1/2Nux increase up to 3.87% when φ increases from 0 to 0.04, and 6.69% when γ increases from 0.05 to 0.2. Besides, the profiles of the temperature θ(η) and the velocity f’(η) on the first solution incline for larger γ, but their second solutions decline. Moreover, it is noticed that the streamlines are separated into two regions. Finally, it is found that the first solution is stable over time.

Magnetocrystalline Anisotropy and Twinning Stress of 10M and 2M Martensites in Ni-Mn-Ga System

2006 ◽  
Vol 512 ◽  
pp. 195-200 ◽  
Author(s):  
Nariaki Okamoto ◽  
Takashi Fukuda ◽  
Tomoyuki Kakeshita ◽  
Tetsuya Takeuchi
Keyword(s):  
Magnetic Field ◽  
Shear Stress ◽  
Magnetocrystalline Anisotropy ◽  
Anisotropy Constant ◽  
The Other ◽  
Magnetic Shear ◽  
Maximum Value ◽  
Twinning Plane ◽  
Twinning Shear ◽  
The Difference

Ni2MnGa alloy with 10M martensite exhibits rearrangement of martensite variants (RMV) by magnetic field, but Ni2.14Mn0.92Ga0.94 with 2M martensite does not. In order to explain the difference, we measured uniaxial magnetocrystalline anisotropy constant Ku and the stress required for twinning plane movement τreq in these alloys. Concerning the former alloy, the maximum value of magnetic shear stress acting across twinning plane τmag, which is evaluated as |Ku| divided by twinning shear, becomes larger than τr eq. On the other hand, concerning the latter alloy, the maximum of τmag is only one-tenth of τreq at any temperature examined. Obviously, the relation, τmag> τr eq, is satisfied when RMV occurs by magnetic field and vice versa. In this martensite, the large twinning shear of 2M martensite is responsible for small τmag and large τreq.

Dynamics of a disc in a nematic liquid crystal

Soft Matter ◽  
2016 ◽  
Vol 12 (4) ◽  
pp. 1279-1294 ◽  
Author(s):  
Alena Antipova ◽  
Colin Denniston
Keyword(s):  
Magnetic Field ◽  
Liquid Crystal ◽  
Numerical Simulations ◽  
Nematic Liquid Crystal ◽  
Weak Magnetic Field ◽  
Angular Speed ◽  
The Magnetic Field

We explain the motion of a micron-sized ferromagnetic disc immersed in a nematic liquid crystal under the action of a weak magnetic field using numerical simulations. We show that the disc's behaviour can be controlled by the angular speed of the magnetic field and its magnitude.

Effects of magnetic field on blood flow with suspended copper nanoparticles through an artery with overlapping stenosis

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
C. Umadevi ◽  
G. Harpriya ◽  
M. Dhange ◽  
G. Nageswari
Keyword(s):  
Magnetic Field ◽  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Copper Nanoparticles ◽  
Analytical Solutions ◽  
Biomedical Applications ◽  
Flow Resistance ◽  
Cardiac Diseases ◽  
Stenosed Artery

The flow of blood mixed with copper nanoparticles in an overlapping stenosed artery is reported in the presence of a magnetic field. The presence of stenosis is known to impede blood flow and to be the cause of different cardiac diseases. The governing nonlinear equations are rendered dimensionless and attempted under the conditions of mild stenosis. The analytical solutions for velocity, resistance to the flow, wall shear stress, temperature, and streamlines are obtained and analyzed through graphs. The obtained outcomes show that the temperature variation in copper nanoparticles concentrated blood is more and flow resistance is less when compared to pure blood. The investigations reveal that copper nanoparticles are effective to reduce the hemodynamics of stenosis and could be helpful in biomedical applications.

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