Evaporation and drying characteristics of the sessile ferrofluid droplet under a horizontal magnetic field

Abstract From the standpoint of its magnetic anisotropy, stretched rubber is comparable in a first approximation to a uniaxial crystal, in which the direction of the axis is the same as the direction of elongation. It is possible to measure this anisotropy by means of the oscillation method used by Krishnan, Guha and Banerjee in studying crystals. The sample to be examined is suspended in a uniform horizontal magnetic field in such a manner that its axis is horizontal. It is then so arranged that the torsion of the suspension wire is zero when the rubber sample is in a position of equilibrium in the field. The times of oscillation T′ and T for very small angular displacements around this position, in the presence and then in the absence of the magnetic field, are then recorded. In this way the difference between the specific susceptibilities in the direction of the axis and in the horizontal direction perpendicular to the axis is calculated by application of the equation:

Download Full-text

Numerical Solution of Melting Processes for Fixed and Unfixed Phase Change Material in the Presence of Magnetic Field: Simulation of Low Gravity Environment

10.1115/imece2001/htd-24290 ◽

2001 ◽

Author(s):

Y. Asako ◽

E. Gonçalves ◽

M. Faghri ◽

M. Charmchi

Keyword(s):

Magnetic Field ◽

Natural Convection ◽

Phase Change ◽

Phase Change Material ◽

Flow Patterns ◽

Transport Processes ◽

Low Gravity ◽

Horizontal Magnetic Field ◽

Wall Heating ◽

Change Material

Abstract Transport processes associated with melting of an electrically conducting Phase Change Material (PCM), placed inside a rectangular enclosure, under low-gravity environment, and in the presence of a magnetic field is simulated numerically. Electromagnetic forces damp the natural convection as well as the flow induced by sedimentation and/or floatation, and thereby simulating the low gravity environment of outer space. Computational experiments are conducted for both side-wall heating and top-wall heating under horizontal magnetic field. The governing equations are discretized using a control-volume-based finite difference scheme. Numerical solutions are obtained for true low-gravity environment as well as for the simulated-low-gravity conditions resulted by the presence of a horizontal magnetic field. The effects of magnetic field on the natural convection, solid phase floatation/sedimentation, liquid-solid interface location, solid melting rate, and flow patterns are investigated. It is found that the melting under low-gravity environment can reasonably be simulated on earth via applying a strong horizontal magnetic field. However, the flow patterns obtained for the true low-gravity cases are not similar to the corresponding cases solved for the simulated-low-gravity environment.

Download Full-text

Effect of a horizontal magnetic field on convective instabilities in mercury

Journal de Physique Lettres ◽

10.1051/jphyslet:019810042021045500 ◽

1981 ◽

Vol 42 (21) ◽

pp. 455-457 ◽

Cited By ~ 35

Author(s):

S. Fauve ◽

C. Laroche ◽

A. Libchaber

Keyword(s):

Magnetic Field ◽

Horizontal Magnetic Field ◽

Convective Instabilities

Download Full-text

Time scale of the largest imaginable magnetic storm

Nonlinear Processes in Geophysics ◽

10.5194/npg-20-19-2013 ◽

2013 ◽

Vol 20 (1) ◽

pp. 19-23 ◽

Cited By ~ 3

Author(s):

V. M. Vasyliūnas

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Magnetic Storm ◽

Energy Content ◽

Horizontal Magnetic Field ◽

Order Of Magnitude ◽

Magnetosphere Plasma ◽

Time Required ◽

Parameter Values ◽

Magnetic Field Perturbation

Abstract. The depression of the horizontal magnetic field at Earth's equator for the largest imaginable magnetic storm has been estimated (Vasyliūnas, 2011a) as −Dst ~ 2500 nT, from the assumption that the total pressure in the magnetosphere (plasma plus magnetic field perturbation) is limited, in order of magnitude, by the minimum pressure of Earth's dipole field at the location of each flux tube. The obvious related question is how long it would take the solar wind to supply the energy content of this largest storm. The maximum rate of energy input from the solar wind to the magnetosphere can be evaluated on the basis either of magnetotail stress balance or of polar cap potential saturation, giving an estimate of the time required to build up the largest storm, which (for solar-wind and magnetospheric parameter values typical of observed superstorms) is roughly between ~2 and ~6 h.

Download Full-text

DIPOLE-FIELD TYPE MAGNETIC DISTURBANCES AND AURORAL ACTIVITIES

Canadian Journal of Physics ◽

10.1139/p61-033 ◽

1961 ◽

Vol 39 (2) ◽

pp. 350-366 ◽

Cited By ~ 1

Author(s):

B. K. Bhattacharyya

Keyword(s):

Magnetic Field ◽

Current System ◽

Field Vector ◽

Maximum Magnitude ◽

Horizontal Magnetic Field ◽

Auroral Activity ◽

The North ◽

Initial Location ◽

Sequence Relationship ◽

Direction Of Movement

The characteristics of the magnetic field components at Agincourt have been calculated for a current system produced by an electric dipole located in the region of auroral activity near Ottawa. It is noted that, irrespective of the orientation of the dipole, the horizontal magnetic field component rotates in the clockwise and anticlockwise senses for motion of the dipole towards the east and the west respectively, when the dipole is situated in the north half of the sky as seen from the observing station.Next, the magnetograms obtained at Agincourt have been studied at those times of the night when auroral activity was recorded in the all-sky camera photographs at Springhill near Ottawa. It is noted that the horizontal magnetic field describes a loop during a particular phase of auroral activity because of its gradual growth and decay. The distributions of clockwise and anticlockwise rotations with respect to local time are found to be very similar in many respects to those of auroral motions to the east and west respectively. The sense of rotation of the loop is predominantly anticlockwise in the early part of the night and clockwise in the late hours of the night.It is found that eastward and westward orientations of the dipole are the most probable ones. The direction of movement and the initial location of the predominant auroral form in the sky are found to tally well with those of the dipole deduced from a study of the magnetograms.It seems that there is a time sequence relationship between successive phases of auroral activity and changes of characteristics of the loops described by the horizontal magnetic field vector. The area of a loop and the maximum magnitude of the field vector in the loop appear to be related to the brightness and horizontal extent of the auroral forms.

Download Full-text

Multi-point ground-based ULF magnetic field observations in Europe during seismic active periods in 2004 and 2005

Natural Hazards and Earth System Science ◽

10.5194/nhess-8-501-2008 ◽

2008 ◽

Vol 8 (3) ◽

pp. 501-507 ◽

Cited By ~ 5

Author(s):

G. Prattes ◽

K. Schwingenschuh ◽

H. U. Eichelberger ◽

W. Magnes ◽

M. Boudjada ◽

...

Keyword(s):

Magnetic Field ◽

Field Intensity ◽

Seismic Activity ◽

Magnetic Field Intensity ◽

Field Measurements ◽

Fluxgate Magnetometer ◽

Vertical Magnetic Field ◽

Earthquake Epicenter ◽

Electromagnetic Noise ◽

Horizontal Magnetic Field

Abstract. We present the results of ground-based Ultra Low Frequency (ULF) magnetic field measurements observed from June to August 2004 during the Bovec earthquake on 12 July 2004. Further we give information about the seismic activity in the local observatory region for an extended time span 2004 and 2005. ULF magnetic field data are provided by the South European Geomagnetic Array (SEGMA) where the experience and heritage from the CHInese MAGnetometer (CHIMAG) fluxgate magnetometer comes to application. The intensities of the horizontal H and vertical Z magnetic field and the polarization ratio R of the vertical and horizontal magnetic field intensity are analyzed taking into consideration three SEGMA observatories located at different close distances and directions from the earthquake epicenter. We observed a significant increase of high polarization ratios during strong seismic activity at the observatory nearest to the Bovec earthquake epicenter. Apart from indirect ionospheric effects electromagnetic noise could be emitted in the lithosphere due to tectonic effects in the earthquake focus region causing anomalies of the vertical magnetic field intensity. Assuming that the measured vertical magnetic field intensities are of lithospheric origin, we roughly estimate the amplitude of electromagnetic noise in the Earths crust considering an average electrical conductivity of <σ>=10−3 S/m and a certain distance of the observatory to the earthquake epicenter.

Download Full-text

Magnetoconvection in a horizontal duct flow at very high Hartmann and Grashof numbers

Journal of Fluid Mechanics ◽

10.1017/jfm.2021.987 ◽

2021 ◽

Vol 931 ◽

Author(s):

R. Akhmedagaev ◽

O. Zikanov ◽

Y. Listratov

Keyword(s):

Magnetic Field ◽

Magnetic Field Effect ◽

Dimensional Structure ◽

Two Dimensional ◽

Duct Flow ◽

Mean Flow ◽

Horizontal Magnetic Field ◽

Nuclear Fusion Reactor ◽

Dimensional Approximation ◽

Very High

Direct numerical simulations and linear stability analysis are carried out to study mixed convection in a horizontal duct with constant-rate heating applied at the bottom and an imposed transverse horizontal magnetic field. A two-dimensional approximation corresponding to the asymptotic limit of a very strong magnetic field effect is validated and applied, together with full three-dimensional analysis, to investigate the flow's behaviour in the previously unexplored range of control parameters corresponding to typical conditions of a liquid metal blanket of a nuclear fusion reactor (Hartmann numbers up to $10^4$ and Grashof numbers up to $10^{10}$ ). It is found that the instability to quasi-two-dimensional rolls parallel to the magnetic field discovered at smaller Hartmann and Grashof numbers in earlier studies also occurs in this parameter range. Transport of the rolls by the mean flow leads to magnetoconvective temperature fluctuations of exceptionally high amplitudes. It is also demonstrated that quasi-two-dimensional structure of flows at very high Hartmann numbers does not guarantee accuracy of the classical two-dimensional approximation. The accuracy deteriorates at the highest Grashof numbers considered in the study.

Download Full-text