Magnetic field effect on natural convection and entropy generation in a half-moon shaped cavity with semi-circular bottom heater having different ferrofluid inside

In this study magneto-hydrodynamic convection in a half-moon shaped cavity filled with ferrofluid has been analyzed numerically. The cavity has two semi-circular bottom heaters and effect of the distance between these two heaters (λ=0.1,0.4) has been thoroughly investigated. Numerical simulation has been carried out for a wide range of Rayleigh number (Ra=103∼107), Hartmann number (Ha=0∼100) and inclination angle of magnetic field (γ=0°∼90°) to understand the flow field, thermal field and entropy generation respectively. Cobalt-kerosene and Fe3O4 -water ferrofluids are used for the present investigation and considered as a single phase fluid. Galerkin weighted residual method of finite element analysis has been used for numerical solution. The code validation and grid independency test have been carried out to justify the numerical accuracy. It has been observed that increment of magnetic field reduces the heat transfer rate, whereas increment of heater distance augments the heat transfer rate significantly. Results are discussed on the basis of Nusselt number (Nu), Bejan number (Be) and shown by contours and 3D plots. It has also been found that λ=0.4 always shows better heat transfer rate and entropy optimization.