Effects of a Magnetic Modulation on the Stability of a Magnetic Liquid Layer Heated From Above

Aniss, Saı̈d; Belhaq, Mohamed; Souhar, M.

doi:10.1115/1.1370501

Cited by 58 publications

(32 citation statements)

References 13 publications

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“…An interesting case consists of applying an external magnetic field of a constant or spatially varying gradient. The effect of a time-sinusoidal magnetic field on the onset of convection in a horizontal magnetic fluid layer heated from above and bounded by isothermal non-magnetic boundaries has been considered by Aniss et al (2001). Self-oscillatory convection caused by the Soret effect in ferrofluids has been predicted by Shliomis and Souhar (2000).…”

Section: Introductionmentioning

confidence: 99%

The Effect of Magnetic Field Dependent Viscosity on Thermosolutal Convection in a Ferromagnetic Fluid Saturating a Porous Medium

2005

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The effect of magnetic field dependent viscosity on thermosolutal convection in a ferromagnetic fluid saturating a porous medium is considered for a fluid layer heated and soluted from below in the presence of uniform magnetic field. Using linearized stability theory and normal mode analysis, an exact solution is obtained for the case of two free boundaries. For case of stationary convection, medium permeability has a destabilizing effect, whereas a stable solute gradient and magnetic field dependent viscosity have a stabilizing effect on the system. In the absence of magnetic field dependent viscosity, the destabilizing effect of non-buoyancy magnetization is depicted but in the presence of magnetic field dependent viscosity non-buoyancy magnetization may have a destabilizing or stabilizing effect on the onset of instability. The critical wave number and the critical magnetic thermal Rayleigh number for the onset of instability are also determined numerically for sufficiently large values of buoyancy magnetization parameter M 1 and the results are depicted graphically. The principle of exchange of stabilities is found to hold true for the ferromagnetic fluid saturating a porous medium heated from below 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 the non-existence of overstability is also obtained. The paper also reaffirms the qualitative findings of earlier investigations which are, in fact, limiting cases of the present study.

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Section: Introductionmentioning

confidence: 99%

The Effect of Magnetic Field Dependent Viscosity on Thermosolutal Convection in a Ferromagnetic Fluid Saturating a Porous Medium

2005

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“…This effect was analyzed for a liquid layer heated from below or from above (stable or unstable equilibrium configurations). Here the onset of convection presents a competition between harmonic and subharmonic modes; see for instance [3,8,9,[12][13][14][15][16]. A similar modulation to the gravitational one can be realized in a horizontal ferromagnetic liquid layer heated from above and submitted to a time-periodic external magnetic field instead of vertical vibrations [11,12].…”

Section: Introductionmentioning

confidence: 93%

“…Here the onset of convection presents a competition between harmonic and subharmonic modes; see for instance [3,8,9,[12][13][14][15][16]. A similar modulation to the gravitational one can be realized in a horizontal ferromagnetic liquid layer heated from above and submitted to a time-periodic external magnetic field instead of vertical vibrations [11,12]. The other type of modulation [14][15][16][17][18][19][20][21][22][23][24][25], in which the temperatures is oscillating at the boundaries, is mainly concentrated in a boundary layer whose thickness decreases with increasing frequency of modulation.…”

Section: Introductionmentioning

confidence: 96%

Effect of quasi-periodic gravitational modulation on the convective instability in Hele-Shaw cell

Boulal

Aniss

Belhaq

et al. 2008

International Journal of Non-Linear Mechanics

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The aim of the present paper is to examine the effect of a quasi-periodic gravitational modulation on the onset of convective instability in Hele-Shaw cell. The quasi-periodic modulation considered here consists in a modulation having two incommensurate frequencies. This study is an extension of a previous work by Aniss et al. [10] in which only a periodic gravitational modulation was considered. We have shown that for P r = O(1) or P r >> 1, the gravitational modulation has no effect on the convective threshold as expected. However, for P r = O(ǫ 2 ), it turns out that a modulation with two incommensurate frequencies has a stabilizing or a destabilizing effect strongly depending on the frequencies ratio.

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“…A previous theoretical investigation [1] has shown that the onset of convection in a horizontal magnetic fluid layer can be influenced by a time-modulated driving force. This driving force is induced by an external magnetic field, which can easily be time-modulated with the frequencies required for the investigations.…”

Section: Introductionmentioning

confidence: 99%

Thermomagnetic convection in magnetic fluids influenced by a time‐modulated magnetic field

Engler

Odenbach

2008

Proc Appl Math and Mech

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Material-and flow properties of magnetic fluids can be influenced by applying an external magnetic field. In this work we will particularly consider the onset of convection in magnetic fluids which is influenced by a magnetic force. In a horizontal magnetic fluid layer the force arises if a temperature gradient and an external magnetic field is applied. The behaviour of the onset of convection is investigated for a static and a time-modulated magnetic field. For the case of a static magnetic field the onset of convection depends on the strength of the field and for a time-modulated magnetic field an additional dependence on the frequency of magnetic field variation is found. The experimental results presented here confirm in principle the theoretical predictions about the influence of static and time-modulated magnetic forces on the onset of convection.

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Effects of a Magnetic Modulation on the Stability of a Magnetic Liquid Layer Heated From Above

Cited by 58 publications

References 13 publications

The Effect of Magnetic Field Dependent Viscosity on Thermosolutal Convection in a Ferromagnetic Fluid Saturating a Porous Medium

The Effect of Magnetic Field Dependent Viscosity on Thermosolutal Convection in a Ferromagnetic Fluid Saturating a Porous Medium

Effect of quasi-periodic gravitational modulation on the convective instability in Hele-Shaw cell

Thermomagnetic convection in magnetic fluids influenced by a time‐modulated magnetic field

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