1998 Volume 38 Issue 5 Pages 421-429
Transient flow in a water bath contained in a cylindrical vessel, being initially at rest and then suddenly set in rotation, was investigated experimentally and numerically. This flow field is a model for molten metal flow in the rotating reactor of materials processing systems. Two different boundary conditions were imposed on the bath surface: solid wall and free surface. Because the Ekman boundary layer developing on the bottom wall (and on the top wall in the former case) became unstable, the flow in the bath was neither purely laminar nor fully turbulent in the course of flow establishment. As one of simplified calculation methods, the kinematic viscosity of liquid was increased artificially in the laminar calculation so that the calculated transient velocity profiles best fitted the presently measured velocity profiles in the water bath with the top wall. This method could approximate the transient velocity profiles in the bath with free surface as well. The flow establishment time in the presence of the top wall became half the value for the free surface.