Analysis of convection effects in capillary-reservoir diffusion measurements

The effects of thresholdless convection on capillaryreservoir diffusion experiments foiliquid metals are math ematically modeled and numerically solved, Thresholdless convection is found to be bounded by the two dimensional diffusion equation when no convection is present and by the one dimensional diffusion equation when infinite convection is present. The commonly used average concentration equation, is found to be applicable when the following constraints are met; the aspect ratio (L/D) is greater than 50; the reservoir to capillary diameter ratio is 25» the reservoir to capillary height ratio is 1; and C is between 0.8 and 0.4. Interdiffusion studies should operate under these restraints. For aspect ratios less than 50 and the remaining condi tions above satisfied, the following approximation is appli cable for self-diffusion studies: c