Binary Nanofluid Convection for Darcy-Brinkman Model in Hydromagnetics

The effect of an externally impressed magnetic field on the onset of convection in a binary nanofluid layer saturating a Darcy-Brinkman model for porous medium is considered in this work. Magnetic field imparts to the fluid rigidity as well as some properties of elasticity which results in the disturbances by new mode of wave propagation. The effects of Brownian motion and thermophoresis due to the presence of nanoparticles and the effects of Dufour and Soret parameters due to the presence of solute have been included in the model under investigation. For analytical study, valid approximations are made in the complex expression for Rayleigh number to get interesting results. The mode of instability is invariably through stationary convection for top heavy distribution of nanoparticles in the fluid. Oscillatory mode of convection is possible for bottom heavy configuration and the frequency of oscillation shows a decrease with an increase in Chandrasekhar number and porosity. It is found that alumina nanoparticles stabilize the water based fluid more than copper nanoparticles which in turn have more stabilizing influence than silver nanoparticles. Fluids do not have much influence of physical properties of nanoparticles on the stability when the particles concentrate more on the bottom of the layer. The stability of the fluid rises appreciably due to the inclusion of magnetic field. Effects of various parameters on the stability of the fluid are studied numerically using Mathematical software and results are shown graphically.