The onset of magnetic nanofluid convection because of selective absorption of radiation

Abstract

This article reports a linear stability analysis of the onset of convection stimulated by selective absorption of radiation in a horizontal layer of magnetic nanofluid (MNF) under the impact of an external magnetic field. The Chebyshev pseudospectral method is utilized to obtain the numerical solution for water-based magnetic nanofluids (MNFs). The confining boundaries of the magnetic nanofluid layer are considered to be rigid–rigid, rigid–free, and free–free. The results are derived for two different conditions, viz., when the system is heated from the below and when the system is heated from the above. It is observed that an increase in the value of the Langevin parameter , diffusivity ratio and a decrease in the value of nanofluid Lewis number , the parameter which represents the impact of selective absorption of radiation and modified diffusivity ratio delays the onset of MNF convection for both the two configurations. Moreover, as the value of concentration Rayleigh number increases, the convection commences easily when the system is heated from the below, whereas the onset of MNF convection gets delayed as the system is heated from the above.

Keywords

• magnetic nanofluids
• radiation absorption
• penetrative convection
• magnetic field
• heat source