Electrohydrodynamic Thermal Instability in a Walters’ (Model B') Rotating Nanofluid Saturating a Porous Medium

Abstract

The onset of thermal instability in a dielectric rotating nanofluid layer saturating a porous medium with vertical AC electric field is investigated by employing Darcy model for porous medium. The rheology of the nanofluid is described by Walters' (model B') for calculating the shear stresses from the velocity gradients. The employed model incorporates the combined effects of movement of the molecules of the fluid striking the nanoparticles, thermophoresis and electrophoresis due to the embedded particles. The boundaries are considered to be stress free. It is assumed that nanoparticle flux is zero on the boundaries. The eigen-value problem is solved analytically using the first approximation of Galerkin method. The Darcy Rayleigh number for onset of nonoscillatory (stationary) modes is obtained. The effects of the modified Taylor number, the AC electric Rayleigh number, the Lewis number, the modified diffusivity ratio, nanoparticles Rayleigh number and medium porosity have been discussed. The kinematic viscoelasticity accounting for rheology of the nanofluid has no effect on the stationary convection for Walters' (model B') nanofluids and behaves like an ordinary Newtonian nanofluid. Oscillatory convection has been ruled out under the considered boundary conditions.

Effects of rotation on Jeffrey nanofluid flow saturated by a porous medium

“…The right-hand side of equation ( 27) is negative if 0, n R  this shows the the medium porosity delays the stationary convection for bottom-heavy configuration and if 0, n R  the medium porosity advances the stationary convection. which is in an agreement with the results derived by Nield and Kuznetsov [4], Chand and Rana [25], Chand et al [28], Rana et al [29] and Ahmad et al [30].…”

“…Chandrasekhar [17] examined the effect of rotation on the Bénard convection which was later extended by Vadasz [18] for a porous medium layer, and Sharma and Rana [19] studied it for the case of viscoelastic fluid and others [20][21][22][23]. Various researchers have studied the effect of rotation on thermal instability by taking different types of viscoelastic fluids [24][25][26][27][28][29][30], and they found that rotation advances the stationary convection.…”

Three-Dimensional Simulation of a Small-Scale Electrodialysis Process for Domestic Use

“…Application arises in astronomy and geophysics as well as in connection with numerous engineering problems, such as liquid metal cooling of nuclear reactors, electromagnetic casting of metals, MHD power generation and propulsion. One of the most important applications of this effect is pumping where the main factor responsible for the flow of the fluid is the Lorentz force; its expression is given by the following equation (Al-Habahbeh et al 2016, Reddy et al 2019, Rana et al 2019):…”

Volumetric heating and AC electric field effects on porous convection with general boundary conditions

“…Maekawa et al 20 studied theoretically the onset of EC on buoyancy and Marangoni convection in a dielectric fluid layer under the influence of AC and DC electric fields. Besides, many studies of ETC have appeared incorporating various other effects, for example, rotation, [21][22][23][24][25][26][27][28] viscoelasticity of the dielectric fluid, [29][30][31] volumetric heat source, [32][33][34] surface tension and variable internal heating, 35 elastico-viscous nanofluid, [36][37][38][39] and so on.…”