Triple- Diffusive Convection in a Magnetized Ferrofluid with MFD Viscosity Saturating a Porous Medium: A Nonlinear Stability Analysis

• Published in: Research Journal of Science and Technology 2013-01, Vol.5 (1), p.1-1
• Main Authors: Chand, Suresh, Kango, S K, Singh, Vikram
• Format: Article
• Language: English
• Subjects: Convection
• ISSN: 0975-4393; 2349-2988

A nonlinear stability analysis is performed for a triple- diffusive convection in a magnetized ferrofluid with magnetic field - dependent viscosity (MFD)saturating a porous for stress- free boundaries. The major mathematical emphasis is on how to control the non-linear terms caused by magnetic body force and inertia forces. A suitable generalized energy functional is introduced to perform the nonlinear energy stability analysis. It is found that nonlinear critical stability magnetic thermal Rayleigh number does not coincide with that of linear instability, and thus indicate that the subcritical instabilities are possible. However, it is noted that in case of non-ferrofluid global nonlinear stability Rayleigh number is exactly same as that of linear instability. For lower values of magnetic parameters, this coincidence is immediately lost. The effects of magnetic parameter M^sub 3^, solute gradients S ^sub 1^ & S^sub 2^, Darcy number D^sub a^ and MFD viscosity parameter δ, on the subcritical instability region have also been analyzed. The solutes gradients S ^sub 1^ & S^sub 2^ have stabilizing effect, because both N^sub ef^ , N^sub lf^ increases as solute gradients increases and Darcy number has a destabilizing effect, because both N^sub ef^ , N^sub lf^ decreases as D^sub a^ increases. It has also been observed that in the presence of MFD viscosity (δ), both N^sub ef^ ,N^sub lf^ decrease for lower values of M^sub 3^ and increase for higher values of M^sub 3^.