Effect of Local Magnetic Fields on Electrically Conducting Fluid Flow and Heat Transfer

The prediction of electrically conducting fluid past a localized zone of applied magnetic field is the key for many practical applications. In this paper, the characteristics of flow and heat transfer (HI) for a liquid metal in a rectangular duct under a local magnetic field are investigated numerically using a three-dimensional model and the impact of some parameters, such as constrainment factor, κ, interaction parameter, N, and Reynolds number, Re, is also discussed. It is found that, in the range of Reynolds number 100 ≤ Re ≤ 900, the flow structures can be classified into the following four typical categories: no vortices, one pair of magnetic vortices, three pairs of vortices and vortex shedding. The simulation results indicate that the local heterogeneous magnetic field can enhance the wall-heat transfer and the maximum value of the overall increment of HI is about 13.6%. Moreover, the pressure drop penalty (ΔP_penalty) does not increasingly depend on the N for constant κ and Re. Thus, the high overall increment of HI can be obtained when the vortex shedding occurs.