Numerical modelling of transport in a liquid diffusion couple shear cell

A model is developed to explore some important issues, such as the effects of the rate of shear on the mixing of the liquid charges, the actual solute distribution at the start of the diffusion anneal period and the effect of a local reduction in liquid charge diameter on the measurement of a liquid diffusion coefficient. A numerical simulation with a grid sliding technique was used to simulate the movable computational domain. The computed results show that the shearing rate has only a small effect on the initial distribution of the solute at the moment when the two liquid columns become aligned, and that the region over which the solute concentration changes from that of the solvent charge to that of the solute-rich charge of the diffusion couple will be very narrow. However, the simulated results reveal that strong convection is produced due to shearing and that the disturbed region is much bigger than the zone over which the solute distribution is disrupted. The convection induced by shearing dissipates within 8 s after the termination of the shearing action for a shear cell with liquid column of 1.5 mm diameter and shear at rates of 4-40 mm s(-1). The simulated results also indicate that a small void (approximately one-sixth of the diameter cross-section) in the liquid solvent near the sheared interface does not affect development of the initial solute concentration profile and its subsequent change with diffusion through the interface.