Onset of Convection in Porous Medium Saturated by Viscoelastic Nanouid: More Realistic Result

The present paper deals with the linear thermal instability analysis of viscoelastic nanofluid saturated porous layer. We consider a set of new boundary conditions for the nanoparticle fraction, which is physically more realistic. The new boundary condition is based on the assumption that the nanoparticle fraction adjusts itself so that the nanoparticle flux is zero on the boundaries. We use Oldroyd-B type viscoelastic fluid that incorporates the effects of Brownian motion and thermophoresis. Expressions for stationary and oscillatory modes of convection have been obtained in terms of the Rayleigh number, which are found to be functions of various parameters. The numerical results have been presented through graphs.