Experimental and computational study of flow instabilities in a model of Czochralski growth

The results of experimental modeling of Czochralski flow of large-Prandtl-number oxide melts are reported. An instability mechanism resulting in cold plumes detaching from the cold crystal and then descending towards the crucible bottom is observed. With the increase of the temperature difference or crystal rotation the baroclinic instability mechanism, characterized by three-dimensional oscillations of a cold jet descending along the symmetry axis, becomes dominant. The experiments are carried out for different silicone oils characterized by different Prandtl numbers and for varying crystal/crucible radii ratio. Results of computational modeling results qualitatively agree with the experimental observations. Possible reasons for the quantitative disagreement are discussed.