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Steady tearing mode instabilities with a resistivity depending on a flux function

Atanda Boussari, Erich Maschke, Bernard Saramito (2010)

ESAIM: Mathematical Modelling and Numerical Analysis

We consider plasma tearing mode instabilities when the resistivity depends on a flux function (ψ), for the plane slab model. This problem, represented by the MHD equations, is studied as a bifurcation problem. For so doing, it is written in the form (I(.)-T(S,.)) = 0, where T(S,.) is a compact operator in a suitable space and S is the bifurcation parameter. In this work, the resistivity is not assumed to be a given quantity (as usually done in previous papers, see [1,2,5,7,8,9,10], but it depends...

Su un problema di instabilità gravitazionale di un fluido in presenza di correnti di Hall e di ion slip

Giulio Mattei (1988)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

In questo lavoro si studia la instabilità gravitazionale di un fluido comprimibile, elettroconduttore, descritto dalle equazioni della magnetofluidodinamica in presenza delle correnti di Hall e di ion slip. Si determina la condizione per la instabilità relativa ad una classe di perturbazioni assialsimmetriche.

The effect of a magnetic field on the onset of Bénard convection in variable viscosity couple-stress fluids using classical Lorenz model

Venkatesh Ramachandramurthy, Nagasundar Kavitha, Agrahara Sanjeevmurthy Aruna (2022)

Applications of Mathematics

The Rayleigh-Bénard convection for a couple-stress fluid with a thermorheological effect in the presence of an applied magnetic field is studied using both linear and non-linear stability analysis. This problem discusses the three important mechanisms that control the onset of convection; namely, suspended particles, an applied magnetic field, and variable viscosity. It is found that the thermorheological parameter, the couple-stress parameter, and the Chandrasekhar number influence the onset of...

The Effect of Crystal-Melt Surface Energy on the Stability of Ultra-Thin Melt Films

M. Beerman, L. N. Brush (2008)

Mathematical Modelling of Natural Phenomena

The stability and evolution of very thin, single component, metallic-melt films is studied by analysis of coupled strongly nonlinear equations for gas-melt (GM) and crystal-melt (CM) interfaces, derived using the lubrication approximation. The crystal-melt interface is deformable by freezing and melting, and there is a thermal gradient applied across the film. Linear analysis reveals that there is a maximum applied far-field temperature in the gas, beyond which there is no film instability. Instabilities...

Unconditional nonlinear exponential stability in the Bénard problem for a mixture: necessary and sufficient conditions

Giuseppe Mulone, Salvatore Rionero (1998)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

The Lyapunov direct method is applied to study nonlinear exponential stability of a basic motionless state to imposed linear temperature and concentration fields of a binary fluid mixture heated and salted from below, in the Oberbeck-Boussinesq scheme. Stress-free and rigid surfaces are considered and absence of Hopf bifurcation is assumed. We prove the coincidence of the linear and (unconditional) nonlinear critical stability limits, when the ratio between the Schmidt and the Prandtl numbers is...

Unconditional nonlinear stability in a polarized dielectric liquid

Giuseppe Mulone, Salvatore Rionero, Brian Straughan (1996)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

We derive a very sharp nonlinear stability result for the problem of thermal convection in a layer of dielectric fluid subject to an alternating current (AC). It is particularly important to note that the size of the initial energy in which we establish global nonlinear stability is not restricted whatsoever, and the Rayleigh-Roberts number boundary coincides with that found by a formal linear instability analysis.

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