Anisotropy of flow and transition between mixing regimes in physical model of directional solidification

V. Geża^{1, 2} - B. Nacke¹ - E. Baake¹ - A. Jakoviċs²

¹ Institute of Electrotechnology, Leibniz University of Hannover
² Laboratory for Mathematical Modelling of Environmental and Technological Processes, University of Latvia

Abstract
This paper aims to provide an insight into the aspects of turbulence anisotropy in the directional solidification (DS) method, which is widely used for the growth of photo-voltaic silicon. In DS crucibles, the melt flow is usually stratified due to strong temperature gradients and this leads to anisotropy of flow and turbulence, which is often neglected in turbulence models used in engineering applications. In experimental measurements, a transition between strong and weak mixing regimes is found. The numerical simulations results provide quantitative measures for anisotropy and vertical heat transfer intensity within the range of different Richardson numbers (0.1 -- 40). Tables 2, Figs 6, Refs 19.