Thermosolutal convection in a horizontal nanofluid layer: Introduction of oscillatory motions

An analytical and numerical analysis is made to investigate the thermosolutal convection in a horizontal nanofluid layer which is heated and soluted from below. The thermal Rayleigh number for bottom heavy configuration of nanoparticles is increased by a substantial amount as compared to that of regular binary fluid layer establishing the fact of heat transfer enhancement in binary nanofluids. The analysis reveals that oscillatory motions come into existence for this case. Also, density variations caused by heat at the bottom competes with the density gradient caused by nanoparticles and solute concentration at the bottom of the layer leads to oscillatory convection followed by stationary convection. The effect of concentration Rayleigh number, solute Rayleigh number, modified diffusivity ratio and nanofluid Lewis number on the stability of layer using alumina-water nanofluid has been studied and presented graphically.