The three-dimensional time-dependent flow of oxide melts in a Czochralski system using the accelerated crucible rotation technique was numerically investigated. The simultaneous effect of the double-crucible method, which enables separation of feed material and a growing crystal, on the growth of long homogeneous crystals was also investigated. Several types of crucible rotations were used to investigate the stabilization of convection of lithium niobate melt. The calculations clarified that time-dependent crucible rotation with acceleration can effectively stabilize the convection of the melt, especially in combination with the double-crucible technique. (C) 2003 The Electrochemical Society.