Electroconvection in Rotating Jeffrey Nanofluid Saturating Porous Medium: Free–Free, Rigid-Free, Rigid–Rigid Boundaries

Abstract

The impact of rotation and the boundaries on the initiation of convective instability in a rheological nanofluid layer heated beneath saturated by a porous media with the inclusion of an AC electric field (vertical) is studied employing linear stability analysis. The stationary convective stability of rheological nanofluid is customarily established utilizing Buongiorno model for nanoparticles and Jeffrey model for rheological behavior of regular fluid. The Buongiorno model deployed for nanofluids incorporates the influence of thermophoresis and Brownian motion. Using the normal mode technique, the set of coupled differential equations is solved analytically for both stress-free boudaries and numerically by using the Galerkin-type Weighted Residual Method (GWRM) for top-free, bottom-rigid and rigid–rigid bounding surfaces. The numerical computed values of stationary thermal Rayleigh number are presented graphically for three distinct combinations of boundary conditions. The Taylor number accounting for rotation parameter, Jeffrey parameter, and nanofluid Lewis number delay the start of stationary convection, whereas electric field and concentration Rayleigh number destabilize a system for three groups of boundaries. The bottom-/top-heavy nanofluids are found to be more/less stable. Rigid–rigid boundaries augment the stability in a more pronounced manner than that of the stress-free and rigid-free boundaries. The conditions for non-occurrence of over stability are also derived. This study is of great significance in many metallurgical processes including megma flow, deep convective chimneys, polymer solutions, microfluidic devices and blood flow in micro circulatory systems. An excellent coincidence is found admist present paper and the earlier published work.