1 INTRODUCTION The evolution of the curvilinear liquid-solid interface in the crystallization processes of undercooled melts and supersaturated solutions is responsible for the properties of solidifying materials [1-9]. Thus, for example, the crystallization front displaces a part of the dissolved impurity into the liquid phase and another part of the impurity is absorbed into the solid material during this process. Thus, the melt immediately upstream of the front is enriched with impurity.
