NUMERICAL STUDY ON TRANSIENT CONVECTION IN FLOAT-ZONE INDUCED BY G-JITTERS

The transient convection in the float zone caused by axial g-jitters i s studied. A numerical code based on the finite difference method is d eveloped to solve time-dependent buoyancy and surface tension driven c onvections in the float zone with non-deformable surface. First, the e ffects of g-jitters on the float zone crystal growth of bismuth silica te (BSO) in microgravity environment are investigated. The ranges of f requency and amplitude which may cause a vigorous transient convection in the BSO float zone are predicted. Second, the numerical analysis i s extended to a parametric study to investigate more general character istics of transient convection induced by the g-jitter. The examined p roblem is defined and is characterized with a set of parameters of the Marangoni number, Prandtl number, amplitude and frequency of the g-ji tter. The responses of both temperature and velocity to the g-jitters are examined for various combinations of these parameters.