Study of Melting of a Horizontal Ice Layer with a Combined Effect of Temperature and Concentration

对方形空腔内水平竖直冰板融化成氯化钙水溶液的过程进行了实验和数值研究。浸入水溶液中的冰板与冰中的温度降低自发地融化，即使在冰和刚刚开始融化的水溶液之间没有温度差，这是不可能通过用热扩散控制的经典Stefan问题来预测的。一个新的概念的质量扩散控制融化的数值方法定量预测的冰的温度，瞬时融化的质量，和双扩散对流在液体中的突然抑郁症。由于浓度诱导的优势对流，熔化面上方的熔化量比下方的大一倍左右。从底部熔化的数值模拟结果与实验结果吻合较好，但与实验结果相比，数值模拟结果要小40%左右。基于层流假设的数值计算方法难以预测熔化表面上方的熔化量，因为在熔化表面上出现了一个由浮力引起的盐指状的小喷口。此外，还发现，目前的数值预报将需要设置一个非常小的网格尺寸小于约0.1mm，由于非常薄的浓度边界层最接近的熔化前沿。

Experimental and numerical investigations are carried out of the melting of a horizontal vertical ice plate into a calcium chloride aqueous solution inside a square cavity. The ice plate immersed into the aqueous solution melts spontaneously associated with temperature depression in the ice even when there is no temperature difference between the ice and the aqueous solution just beginning of the melting, which is not possible to predict through the classical Stefan problem controlled with a thermal diffusion. A numerical method with a new concept of a mass diffusion controlled melting predicts quantitatively an abrupt depression in the temperature of the ice, a transient melting mass, and a double diffusive convection in the liquid. The melting amount from above melting surface is about double larger than that from below due to the concentration induced predominant convection. The numerical results for the melting from below predicts well the experiment, however, predicts less about 40% compared with the experiment. The present numerical treatment based on the laminar assumption is difficult to predict the melting amount from above melting surface since it appeared a very small spouts induced with the buoyancy like a salt finger on the melting surface. Moreover, it is also found that the present numerical prediction will require to set a very smaller mesh size less than about 0.1mm due to the very thin concentration boundary layer closest to the melting front.