Effect of input diffusivity in an axisymmetric mass diffusivity model for liquid metals with an applied magnetic field.

Depending on the magnitude of the diffusivity, convective contamination may result in erroneous measurement of mass diffusivity even in microgravity. The effect of natural or buoyant convection is numerically investigated for liquid germanium with an axisymmetric model using two different magnetic field strengths and four heat transfer conditions. Since the reported input diffusivity value may vary due to inaccuracies in measurements, an order of magnitude lower and higher input diffusivity from the base value of D0 = 2 x 10(-4) cm2/sec was used to evaluate the behavior of liquid germanium in the presence of a magnetic field. From the numerical results, the temperature nonuniformity and the flow velocities in the liquid vary according to the input diffusivity (i.e., an order of magnitude lower and higher than the base cases). The heat transfer pattern is important in achieving a larger temperature nonuniformity in the liquid during the experiments. A stronger magnetic field can tolerate a higher temperature nonuniformity as expected.