3-D Simulations of Diffusivity Measurements in Liquids with an Applied Magnetic Field

The effect of convective contamination in self-diffusivity experiments of liquid metals is predicted via a three-dimensional (3-D) model that includes an applied magnetic field. A uniform heat flux is applied at the sidewall of the cylindrical ampoule, and heat losses are allowed at the top and bottom walls of the ampoule. A wide range of a uniform, steady, axial magnetic field (from moderate to very strong) is considered in the model. Since the thermal P´eclet number, Pe, is very small for the parameters of iInterest, convective heat transfer is neglected. A large iInteraction parameter, N, suggests that the flow is inertialess. The temperature and flow problems are solved at steady state while the time-dependent concentration problem is determined for various mass P´eclet numbers, Pem. In all cases, the output D (i.e., with convective contamination) increases with an increase in the temperature nonuniformity Tθ . The radial and azimuthal velocities are much smaller than the axial velocity in each case. A stronger magnetic field can tolerate a higher temperature non-uniformity Tθ, but Tθ is still less than 0.025K with a 5T magnetic field for convective contaminations to be less than 5% of the total mass flux.