Ramesh Chand

Oscillating Convection of Nanofluid in Porous Medium

In this paper, oscillatory convection in a horizontal layer of nanofluid in porous medium is studied. For porous medium, Darcy model is applied. A linear stability theory and normal mode analysis method is used to find the solution confined between two free boundaries. The onset criterion for oscillatory convection is derived analytically and graphically. Regimes of oscillatory and non-oscillatory convection for various parameters are derived. The effects of Lewis number, concentration Rayleigh number, Prandtl–Darcy number (Vadasz Number) and modified diffusivity ratio on the oscillatory convection are investigated graphically. We examine the validity of ‘PES’ and concluded that ‘PES’ is not valid for the problem.

Dufour and Soret Effects on the Thermosolutal Instability of Rivlin- Ericksen Elastico-Viscous Fluid in Porous Medium

Dufour and Soret effects on the convection in a horizontal layer of Rivlin-Ericksen elastico- viscous fluid in porous medium are considered. For the porous medium, the Darcy model is used. A linear stability analysis based upon normal mode analysis is employed to find a solution of the fluid layer confined between two free boundaries. The onset criterion for stationary and oscillatory convection has been derived analytically, and graphs have been plotted, giving various numerical values to various parameters, to depict the stability characteristics. The effects of the Dufour parameter, Soret parameter, solutal Rayleigh number, and Lewis number on stationary convection have been investigated.

Magneto Convection in a Layer of Nanofluid With Soret Effect

Abstract Double diffusive convection in a horizontal layer of nanofluid in the presence of uniform vertical magnetic field with Soret effect is investigated for more realistic boundary conditions. The flux of volume fraction of nanoparticles is taken to be zero on the isothermal boundaries. The normal mode method is used to find linear stability analysis for the fluid layer. Oscillatory convection is ruled out because of the absence of the two opposing buoyancy forces. Graphs have been plotted to find the effects of various parameters on the stationary convection and it is found that magnetic field, solutal Rayleigh number and nanofluid Lewis number stabilizes fluid layer, while Soret effect, Lewis number, modified diffusivity ratio and nanoparticle Rayleigh number destabilize the fluid layer.

ON THE ONSET OF RAYLEIGH–BÉNARD CONVECTION IN A LAYER OF NANOFLUID IN HYDROMAGNETICS

Rayleigh–Benard convection in a horizontal layer of nanofluid in the presence of uniform vertical magnetic field is investigated by using Galerkin weighted residuals method. The model used for the nanofluid describes the effects of Brownian motion and thermophoresis. Linear stability theory based upon normal mode analysis is employed to find expressions for Rayleigh number and critical Rayleigh number. The boundaries are considered to be free–free, rigid–rigid and rigid–free. The influence of magnetic field on the stability is investigated and it is found that magnetic field stabilizes the fluid layer. It is also observed that the system is more stable in the case of rigid–rigid boundaries and least stable in case of free–free boundaries. The expression for Rayleigh number for oscillatory convection has also been derived for free–free boundaries.

Megneto-convection in a Layer of Maxwell Visco-Elastic Fluid in a Porous Medium with Soret Effect

Double Diffusive convection in a horizontal layer of Maxwell visco-elastic fluid in a porous medium in the presence of constant vertical magnetic field and Soret coefficient is investigated. Flow in porous medium is characterized by Darcy model. The normal mode method is used to find linear stability analysis for the fluid layer confined between two free-free boundary surfaces. The stability criterions for stationary and oscillatory convection have been derived. Effects of various parameters on the stationary have been obtained analytically and graphically.

On the Onset of Electrohydrodynamic Instability of Rivlin-Ericksen Viscoelastic Dielectric Fluid Layer

In this paper we investigate the effect of AC electric field on the onset of instability of an elastico-viscous Rivlin-Ericksen dielectric fluid layer stimulated by the dielectrophoretic force due to the variation of dielectric constant with temperature. By applying linear stability theory and normal mode analysis method, we derive the dispersion relation describing the influence of viscelasticity and AC electric field. For the case of stationary convection, it is observed that Rivlin-Ericksen fluid behaves like an ordinary Newtonian fluid whereas AC electric field hastens the stationary convection. The present results are in good agreement with the earlier published results.