Numerical and statistical analysis on unsteady magnetohydrodynamic convection in a semi-circular enclosure filled with ferrofluid

Abstract

In this paper unsteady magnetohydrodynamic convection has been analyzed using numerical and statistical techniques for a semicircular-shaped enclosure filled with ferrofluid. Cobalt–kerosene ferrofluid is considered for the present investigation. Galerkin weighted residuals method of finite element analysis is adopted for the numerical simulation. The effects of Rayleigh number (Ra), solid volume fraction (φ) of ferrofluid and Hartmann number (Ha) are considered as pertinent parameters and varied for a wide range of values (Ra = 10^5–10^7, φ = 0–0.15, Ha = 0–50) to capture the flow and thermal interaction phenomena for unsteady situation. It is observed that higher ferrofluid solid volume fraction escalates the heat transfer rate. Enhancing the intensity of external magnetic field (by increasing Ha) retards the heat transfer rate while increment of Ra exhibits improvement on the heat transfer. It is also found that there exists a strong interaction between ferromagnetic particle (cobalt) and base fluid (kerosene) in the presence of magnetic field which can be utilized properly for desired heat transfer augmentation. If φ = 0 (or φ = 0.15) and Ra is changed from 10^5 to 10^7, the linear dependence of Wmax on time changes significantly from positive to negative.