Numerical Simulation Of Thermodiffusion Subjected To Different Gravity Fields

In this work, a typical thermodiffusion experiment on a binary mixture is simulated numerically using a two-dimensional computational fluid dynamics (CFD) code. Three scenarios for gravity have been studied: residual, pure oscillatory, and microgravity micro-accelerations. It was found that less separation of mixture components in the presence of strong gravity fields is due to the formation of buoyancy-driven flows. For the case of pure oscillatory gravity, the effects of the frequency and amplitude are discussed in detail. A critical vibrational Rayleigh number is proposed above which the diffusion process is highly affected by the external excitation. For the case of the microgravity environment, quasi-steady accelerations and g-jitter, both of which are found on the International Space Station, have been considered. Results show g-jitter has a minimal effect on the thermodiffusion experiment. The effects of the residual gravity field were also found to be insignificant in stimulating a strong convection flow.