The effects of thermal gravitational and periodically varying centrifugal forces on the fluid flow and heat transfer are investigated based on a simulation model for the vertical Bridgman crystal growth system with the accelerated crucible rotation technique (ACRT). The principal role of the crucible rotation is analyzed in a sequential manner by varying the complexities of rotating motion; long-time spin-up and ACRT. The long-time spin-up is found to enhance the heat transfer rate in the vicinity of the center. In light of the crystal-growth, this is considered to promote the concavity in the melt/crystal interface shape. By contrast, ACRT is observed to be conductive to maintaining the convexity of the interface through the periodic interaction between the Ekman layers and the inner fluid core. Overall, the present investigation confirms the available results from simulation experiments and crystal-growth runs in that ACRT can improve the melt stirring and the crystal growth rate.