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1

Thermosolutal convection in ferromagnetic fluid

100%

Sunil , Bharti P. K. , Sharma R. C.

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tom Vol. 56, nr 2

117-135

EN

The thermosolutal convection in ferromagnetic fluid is considered for a fluid layer heated and soluted from below in the presence of uniform vertical magnetic field. For the case of two free boundaries, an exact solution is obtained using a linear stability analysis. For the case of stationary convection, magnetization has a destabilizing effect, whereas stable solute gradient has a stabilizing effect on the onset of instability. Graphs have been plotted by giving numerical values to various parameters, to depict the stability characteristics. The principle of exchange of stabilities is found to hold true for the ferromagnetic fluid heated from below in porous medium in the absence of stable solute gradient. The oscillatory modes are introduced due to the presence of the stable solute gradient, which were non-existent in its absence. A sufficient condition for non-existence of the overstability is also obtained.

2

Hall effect on thermal stability of ferromagnetic fluid in the presence of suspended particles

100%

Aggarwal A. K. , Makhija S.

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2012

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tom Vol. 17, no. 2

349-365

EN

This paper deals with the theoretical investigation of the effect of Hall currents and suspended particles on the thermal stability of a ferromagnetic fluid heated from below. For a fluid layer between two free boundaries, an exact solution is obtained using a linearized stability theory and normal mode analysis. A dispersion relation governing the effects of suspended particles and Hall currents is derived. For the case of stationary convection, it is found that the magnetic field has a stabilizing effect, whereas the suspended particles and Hall currents are found to have a destabilizing effect on the system. The critical Rayleigh numbers and wave numbers of the associated disturbances for the onset of stability as stationary convection are obtained. The principle of exchange of stabilities is not valid for the problem under consideration, whereas in the absence of Hall currents (hence magnetic field), it is valid under certain conditions.

3

On a couple-stress Rivlin-Ericksen ferromagnetic fluid heated from below with varying gravity, rotation, magnetic field and suspended particles flowing through a porous medium

84%

Rahul , Sharma N.

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tom Vol. 27, no. 2

177--198

EN

The thermal instability of a couple-stress Rivlin-Ericksen ferromagnetic fluid with varying gravity field, suspended particles, rotation and magnetic field flowing through a porous medium is investigated. The dispersion relation has been developed and solved analytically using the normal mode approach and linear stability theory. The effect of suspended particles, rotation, couple stress, permeability and magnetic field on the fluid layer has been investigated. For stationary conventions, it is found that suspended particles always have a destabilizing effect for λ>0 and a stabilizing effect for λ<0 and couple-stress, magnetic field and permeability of the medium have a stabilizing effect on the thermal instability under certain conditions. In the absence of the rotation couple-stress has a stabilizing effect if λ >0 and a destabilizing effect if λ<0. Rotation has a stabilizing effect if λ >0 and a destabilizing effect if λ<0. In the absence of rotation permeability has a stabilizing effect if λ<0 and a destabilizing effect if λ>0. Magnetisation always has a stabilizing effect ( λ>0 or λ<0).

4

Nonlinear stability problem of ferromagnetic fluids with mass and heat transfer effect

84%

Elhefnawy A. R. F.

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tom Vol. 5, nr 2

253-267

EN

The nonlinear theory of Kelvin-Helmholtz instability is employed to analyze the instability phenomena of ferromagnetic fluids. The effect of both the magnetic field and the mass and heat transfer at the interface on the instability is investigated. The method of multiple scale expansion is. employed for the investigation. It is shown that, for the Rayleigh-Taylor problem, the mass and heat transfer has no effect. In absence of the magnetic field, the system cannot be stabilized by the finite amplitude effects for two semi-infinite fluid layers up to the third-order.

5

Effect of magnetic field on thermosolutal instability of rotating ferromagnetic fluid under varying gravity field

84%

Pundir S. K. , Nadian P. K. , Pundir R.

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tom Vol. 26, no. 1

201--214

EN

This paper deals with the theoretical investigation of the effect of a magnetic field, rotation and magnetization on a ferromagnetic fluid under varying gravity field. To find the exact solution for a ferromagnetic fluid layer contained between two free boundaries, we have used a linear stability analysis and normal mode analysis method. For the case of stationary convection, a stable solute gradient has a stabilizing effect, while rotation has a stabilizing effect if 0λ > and destabilizing effect if 0λ < . Further, the magnetic field is discovered to have both a stabilizing and destabilizing effect for both 0λ > and 0λ < . It is likewise discovered that magnetization has a stabilizing effect for both 0λ > and 0λ < in the absence of the stable solute gradient. Graphs have been plotted by giving numerical values of various parameters. In the absence of rotation, magnetic field and stable solute gradient, the principle of exchange of stabilities is found to hold true for certain conditions.

6

Effect of radiation on Rayleigh-Benard convection in ferromagnetic fluids

84%

Maruthamanikandan S.

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2003

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tom Vol. 8, no 3

449-459

EN

The effect of radiative transfer on the onset of thermal convection in a ferromagnetic fluid layer bounded by two parallel plates and heated from below is considered using Goody's approach. The fluid between the plates absorbs and emits thermal radiation. The Milne-Eddington approximation is employed in obtaining the initial static state. Considering infinitesimal perturbations, the critical magnetic Rayleigh number is obtained using the Rayleigh-Ritz method. It is found that radiation inhibits the onset of convection in both the transparent and opaque media. Further, the opaque medium is shown to release heat for convection more slowly than the transparent medium. It is also found that radiation affects the cell size at the onset of convection in the case of transparent medium only. The results have implications in energy conversion devices and in smart material applications.