scholarly journals Modulationof The Recirculation Region Within Two Inline Square Rib Due toMagnetohydrodynamic FlowUsingComputational Fluid Dynamics

2020 ◽  
pp. 331-336
Author(s):  
Sayahnya Roy ◽  
Gunasekaran N ◽  
Krishnendu Barman ◽  
Koustuv Debnath ◽  
Prantik Sinha
Keyword(s):  
Magnetic Field ◽  
Hartmann Number ◽  
Turbulent Transport ◽  
Mhd Flow ◽  
Recirculation Region ◽  
Wake Region ◽  
Induced Magnetic Field ◽  
Tke Dissipation Rate ◽  
Vorticity Generation ◽  
The Magnetic Field

This study presents the turbulent flow around two square ribs. The numerical computations performed using k–ε model at Reynolds number (Re) = 60000 to quantify the turbulent transport measures. The magnetic field has been applied by Hartmann number (Ha) to generate the magnetohydrodynamic (MHD) flow. The reduction of recirculation region was observed due to the application of magnetic field in the flow. The weak recirculation has an effect on small vorticity generation, which leads to small turbulent kinetic energy (TKE) and TKE dissipation rate generation in the wake region behind the rib. The induced magnetic field is capable of controlling the vortex structures around the square ribs. Results in decreasing magnitude of turbulence level around and between the spaces of the square ribs. It may be hypothesized that by introducing magnetic field, the unwanted vibrations (due to vortex shedding behind the rib) of fully submerged structures can be controlled.

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.

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.

TRANSIENT ELECTROMAGNETIC RESPONSE OF AN INHOMOGENEOUS CONDUCTING SPHERE

Geophysics ◽  
1970 ◽  
Vol 35 (2) ◽  
pp. 331-336 ◽  
Author(s):  
Saurabh K. Verma ◽  
Rishi Narain Singh
Keyword(s):  
Magnetic Field ◽  
Rise Time ◽  
Mineral Deposits ◽  
Electromagnetic Response ◽  
Radial Coordinate ◽  
Induced Magnetic Field ◽  
Transient Electromagnetic ◽  
Unit Step ◽  
Analytic Expressions ◽  
The Magnetic Field

Analytic expressions for the quasi‐static electromagnetic response of a sphere in presence of unit‐step and ramp‐type time varying magnetic fields are derived. The conductivity inside the sphere is assumed to vary linearly with radius, i.e. [Formula: see text], where ρ is radial coordinate, [Formula: see text] is a constant and a is the radius of sphere. Curves showing the decay of the magnetic field for both types of fields are presented. In the case of ramp‐type applied magnetic field, the magnitudes of maxima of the induced magnetic field are found to decrease with increase in the rise time of the applied field and, hence, exciting pulses having small values of rise time should be used. It is believed that the analysis will be useful in the geoelectric exploration for highly conducting mineral deposits.

scholarly journals Analytical Solution for MHD Flow of a Magnetic Fluid within a Thick Porous Annulus

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Shihhao Yeh ◽  
Tsai-Jung Chen ◽  
Jik Chang Leong
Keyword(s):  
Magnetic Field ◽  
Steady State ◽  
Angular Velocity ◽  
Analytical Solution ◽  
Magnetic Fluid ◽  
Mhd Flow ◽  
Induced Magnetic Field ◽  
State Problem ◽  
Closed Form Solutions ◽  
Steady State Problem

The steady-state problem of a magnetic fluid filling a porous annulus between two cylindrical walls under the influence of a nonuniform radially outward magnetic field has been investigated. The cylindrical walls are either electrically perfectly insulated or electrically perfectly conducting. The permeability of the porous annulus increases with its radial location. The governing partial differential equations were derived carefully and closed form solutions for the profiles of the velocity component and the induced magnetic component were obtained. The effect of the strength of the externally applied magnetic field, the permeability of the porous annulus, and the conductivity of the cylindrical walls were examined through the angular velocity components, as well as the induced magnetic field.

scholarly journals On the magnetic field of OH 231.8+4.2

2011 ◽  
Vol 7 (S283) ◽  
pp. 418-419
Author(s):  
Marcelo L. Leal-Ferreira ◽  
Wouter H. T. Vlemmings ◽  
Philip J. Diamond ◽  
Athol Kemball ◽  
Nikta Amiri ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Spherical Symmetry ◽  
Planetary Nebula ◽  
Initial Mass ◽  
Induced Magnetic Field ◽  
Tidal Forces ◽  
Star Binary ◽  
The Magnetic Field

AbstractDuring the transition from an AGB star to a planetary nebula, a large number of low/intermediate initial mass stars loses its spherical symmetry. The process responsible for that change of morphology is, so far, not well understood. The candidates responsible for shaping these objects are (i) a companion to the star (binary/heavy planet) and its tidal forces, (ii) disk interaction and (iii) magnetic fields - or a combination of these. In particular a binary induced magnetic field is a promising option. To study this we observed the polarization of H2O masers in the known binary pre-Planetary Nebula (pPN) OH231.8+4.2. Our results show a magnetic field B|| of ~45 mG is present in the H2O maser region of this pPN.

A Differential Quadrature Solution of MHD Natural Convection in an Inclined Enclosure With a Partition

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Kamil Kahveci ◽  
Semiha Öztuna
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Inclination Angle ◽  
Hartmann Number ◽  
Differential Quadrature ◽  
Flow And Heat Transfer ◽  
Inclined Enclosure ◽  
Vorticity Generation

Magnetohydrodynamics natural convection in an inclined enclosure with a partition is studied numerically using a differential quadrature method. Governing equations for the fluid flow and heat transfer are solved for the Rayleigh number varying from 104 to 106, the Prandtl numbers (0.1, 1, and 10), four different Hartmann numbers (0, 25, 50, and 100), the inclination angle ranging from 0degto90deg, and the magnetic field with the x and y directions. The results show that the convective flow weakens considerably with increasing magnetic field strength, and the x-directional magnetic field is more effective in reducing the convection intensity. As the inclination angle increases, multicellular flows begin to develop on both sides of the enclosure for higher values of the Hartmann number if the enclosure is under the x-directional magnetic field. The vorticity generation intensity increases with increase of Rayleigh number. On the other hand, increasing Hartmann number has a negative effect on vorticity generation. With an increase in the inclination angle, the intensity of vorticity generation is observed to shift to top left corners and bottom right corners. Vorticity generation loops in each region of enclosure form due to multicelluar flow for an x-directional magnetic field when the inclination angle is increased further. In addition, depending on the boundary layer developed, the vorticity value on the hot wall increases first sharply with increasing y and then begins to decrease gradually. For the high Rayleigh numbers, the average Nusselt number shows an increasing trend as the inclination angle increases and a peak value is detected. Beyond the peak point, the foregoing trend reverses to decrease with the further increase of the inclination angle. The results also show that the Prandtl number has only a marginal effect on the flow and heat transfer.

Multiple-relaxation-time lattice Boltzmann study of the magnetic field effects on natural convection of non-Newtonian fluids

2017 ◽  
Vol 28 (11) ◽  
pp. 1750138 ◽  
Author(s):  
Xuguang Yang ◽  
Lei Wang
Keyword(s):  
Magnetic Field ◽  
Relaxation Time ◽  
Power Law ◽  
Lattice Boltzmann ◽  
Hartmann Number ◽  
Magnetic Field Effects ◽  
Multiple Relaxation Time ◽  
Number Formula ◽  
Power Law Index ◽  
The Magnetic Field

In this paper, the magnetic field effects on natural convection of power-law non-Newtonian fluids in rectangular enclosures are numerically studied by the multiple-relaxation-time (MRT) lattice Boltzmann method (LBM). To maintain the locality of the LBM, a local computing scheme for shear rate is used. Thus, all simulations can be easily performed on the Graphics Processing Unit (GPU) using NVIDIA’s CUDA, and high computational efficiency can be achieved. The numerical simulations presented here span a wide range of thermal Rayleigh number ([Formula: see text]), Hartmann number ([Formula: see text]), power-law index ([Formula: see text]) and aspect ratio ([Formula: see text]) to identify the different flow patterns and temperature distributions. The results show that the heat transfer rate is increased with the increase of thermal Rayleigh number, while it is decreased with the increase of Hartmann number, and the average Nusselt number is found to decrease with an increase in the power-law index. Moreover, the effects of aspect ratio have also investigated in detail.

scholarly journals MAGNETOHYDRODYNAMIC HEAT AND MASS TRANSFER FLOW WITH INDUCED MAGNETIC FIELD AND VISCOUS DISSIPATIVE EFFECTS

2014 ◽  
Vol 44 (1) ◽  
pp. 9-17
Author(s):  
S. AHMED ◽  
A. BATIN
Keyword(s):  
Magnetic Field ◽  
Prandtl Number ◽  
Current Density ◽  
Schmidt Number ◽  
Porous Plate ◽  
Mhd Flow ◽  
Induced Magnetic Field ◽  
Dissipative Effects ◽  
Magnetic Prandtl Number ◽  
Mhd Propulsion

An approximate solution to the problem of steady free convective MHD flow of an incompressible viscous electrically-conducting fluid over an infinite vertical isothermal porous plate with mass convection is presented here. A uniform magnetic field is assumed to be applied transversely to the direction of the flow, taking into account the induced magnetic field with viscous and magnetic dissipations of energy. The dimensionless governing equations are solved by using the series solution method. The induced magnetic field, current density, temperature gradient and flow velocity are studied for magnetohydrodynamic body force, magnetic Prandtl number, Schmidt number and Eckert number. It is observed that the induced magnetic field is found to increase with a rise in magnetic Prandtl number. Current density is strongly reduced with increasing magnetic Prandtl number, but enhanced with Schmidt number. The acquired knowledge in our study can be used by designers to control MHD flow as suitable for a certain applications such as laminar magneto-aerodynamics, and MHD propulsion thermo-fluid dynamics.

scholarly journals On the Bottom Magnetic Fields of Millisecond Pulsars

2004 ◽  
Vol 218 ◽  
pp. 47-48
Author(s):  
Chengmin Zhang
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Accretion Rate ◽  
Induced Magnetic Field ◽  
Radio Observations ◽  
Millisecond Pulsars ◽  
Low Field ◽  
Field Evolution ◽  
Field Decay ◽  
The Magnetic Field

The magnetic field strengths of most millisecond pulsars (MSPs) are about 108–9 gauss. The accretion-induced magnetic field evolution scenario here concludes that field decay is related to the accreted mass, that the minimum or bottom field stops at about 108 gauss for Eddington-limited accretion, and scales with the accretion rate as M1/2. The possibility of low field (∼ 107 gauss) MSPs has been proposed for future radio observations.

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