Relaxation behavior in a solution system for crystal growth under microgravity

A hydrodynamic model is used to analyze relaxation behavior in a solution system for crystal growth under microgravity. The relaxations of the dimensionless average velocity of fluid V-av, the dimensionless maximum velocity of fluid V-max, the temperature distribution index S-theta, the concentration distribution index S-phi (see text) and the dimensionless average growth rate of crystal (V) over bar(cg) are calculated under fluctuations of gravity level and the temperature at the growth face of the crystal. The fluctuations are supposed to be perturbations of square pulse with a duration of t(0). It follows from the calculations that the effects of the gravity level fluctuation on the fluid velocities are much greater than those of the temperature fluctuation, but the effects of the latter on the indexes S-theta and S-phi are much greater than those of the former; the effects of the former on (V) over bar(cg) are negligible, but the temperature fluctuation at the growth face of the crystal can obviously change the average growth rate of crystal (V) over bar(cg). Calculations are also executed for the temperature fluctuation at the surface of the wall of the solute source material, Its effects on (V) over bar(cg) are negligible too.