NUMERICAL-ANALYSIS OF TRANSIENT FLOW IN A WATER BATH CONTAINED IN A CYLINDRICAL VESSEL SUDDENLY SET IN ROTATION

Transient flow in a water bath contained in a cylindrical vessel, bein g initially at rest and then suddenly set in rotation, was investigate d experimentally and numerically. This flow field is a model for molte n metal flow in the rotating reactor of materials processing systems. Two different boundary conditions were imposed on the bath surface: so lid wall and free surface. Because the Ekman boundary layer developing on the bottom wall (and on the top wall in the former case) became un stable, the flow in the bath was neither purely laminar nor fully turb ulent in the course of flow establishment. As one of simplified calcul ation methods, the kinematic viscosity of liquid was increased artific ially in the laminar calculation so that the calculated transient velo city profiles best fitted the presently measured velocity profiles in the water bath with the top wall. This method could approximate the tr ansient velocity profiles in the bath with free surface as well. The f low establishment time in the presence of the top wall became half the value for the free surface.