Yoshikazu Teraoka

Crystal Orientation Rotation of Ice During Growth in a Bended Capillary

A control technique of crystal orientation of ice can presumably help to improve freezing processes of various industries. However, the technique without seed ice has not been established yet. The author had found that crystal orientation of ice rotated gradually during high-rate growth along a cooling wall. The purpose of this paper is to examine the crystal orientation rotation of ice during growth in several types of bended capillaries at supercooling temperature. We show that, after growing through the capillaries, c-axis of ice crystal is within a certain angle range. On the basis of the measurement the rotation of crystal orientation before and after the growth through some sections of the capillaries, we constructed an empirical model of c-axis rotating gradually during ice growth in the capillary. The calculation of the model can explain the approach process of c-axis of ice crystal growing in the bended capillary to the specified direction.Copyright

Numerical Analysis of Natural Convection of Suspension With Particle Sedimentation

A new method for the numerical analysis of natural convection of suspension was proposed. Natural convection phenomena of suspension appear in some industrial fields, such as water disposal process and food engineering process. It is difficult to comprehend the behavior of the natural convection of the suspensions, because the convection of the suspension is caused by the interactive effects of the temperature distribution and particle-concentration distribution in the suspension. In this study, a numerical model for the natural convection phenomena of the suspension accompanied by particle sedimentation was constructed. In this model, since the limited number of particles is tracked individually, the movement of each particle which has varied sizes can be achieved. Then the effect of distribution of particle size on the particle-concentration in the suspension can be considered. As a result, it was confirmed that the typical behavior of the natural convection of suspension can be expressed by using this model. Additionally, it was found that the mean Nusselt number of the natural convection of the suspension obtained by using this model shows the same tendency as that of the previous experiments.Copyright