Thermal instability of magnetohydrodynamic couple stress nanofluid in rotating porous medium

A theoretical investigation of thermal instability of magnetohydrodynamic (MHD) couple stress nanofluid is analyzed in rotating porous medium. In this paper an infinite horizontal layer of incompressible electrically conducting couple stress nanofluid in porous medium is considered and the layer is confined between two parallel boundaries. This layer is heated from below and is acted upon by uniform vertical magnetic field and the whole system is rotated uniformly about z ‐direction. Using normal mode analyses a dispersion relation is obtained and this dispersion relation is examined for stationary and oscillatory convection. For stationary convection the effect of various parameters like Couple‐stress parameter C , Lewis number L e , modified diffusivity ratio N A , nanoparticles Rayleigh number R n , porosity ∈, rotation parameter T a and magnetic field parameter Q have been examined and their behavior are displayed through graphs. Oscillatory modes do not exist when and .