Double diffusion convection under sinusoidal modulations of low-frequency vibrations

Double diffusion convection features the coupling of diffusion fluxes driven by the temperature and concentration gradients and the simultaneous existence of the natural convection driven by the buoyancy force. This paper studies the double diffusion convection under different modulations of low-frequency g-jitters in order to evaluate the g-jitter effect on diffusion-dominated experiments in space laboratories. The numerical simulation for a binary mixture of water–isopropanol (90:10 wt%) has shown a dependence of the Soret separation on g-jitter frequency and amplitude. Under the same amplitude, the fluctuation of local properties, i.e., velocity, temperature and concentration, is found to intensify as the g-jitter frequency decreases. When both static residual gravity and oscillatory g-jitter exist, the diffusion process is affected by the nonlinear interaction between individual g-jitters. As the amplitude decreases to 1μg, this nonlinearity becomes less significant than it appears in the high-amplitude scenario.