Abstract
Experiments to demonstrate the behaviors of natural convection along the solidification front in the mold were conducted by the use of KCl solution as the solidification system and with the aid of the thymol blue method as the flow visualization technique.
Experimental results show that with the increase in the solidification time, the maximum velocities of natural convection in the upper region of the mold decrease monotonously and the positions at which the maximum velocity in the lower region of the mold appears approach to the solidification front. For the case of eutectic solution it is found that the mean maximum velocity in the upper region of the mold is proportional to the square root of a modified Grashof number.
Furthermore, the approximate estimations with regard to the natural convection along the dendritic interface are presented on the basis of the boundary layer theory. By comparing the observed data of the mean maximum velocities with those calculated curves, the effects of the fluid flow in mushy zone on the velocity in the boundary layer and on its thickness are investigated.
