The Effect of Magnetic Field Gradient on Ferrofluids Heat Transfer in a Two-Dimensional Enclosure

The two-dimensional, incompressible and laminar time dependant combined natural and magnetic convective heat transfer flow through a magnetic fluid is considered in this paper. The flow takes place in a differentially heated square cavity. The cavity is under the influence of an imposed two dimensional magnetic field which is created by Helmholtz coils. The main objective of this paper is the numerical investigation of the thermo magnetic convection process for different positions of the cavity between the coils and determines the effect of magnetic field gradient on the heat transfer of magnetic fluid. Fluid motion occurs due to both the gradients of the magnetic field and the temperature. The average Nusselt number increases when magnetic field and temperature gradient have the same direction and decreases when they have opposite direction. However the dropping rate of average Nusselt number becomes greater than increasing rate.