FLOW ESTABLISHMENT TIME OF A WATER BATH CONTAINED IN A CYLINDRICAL VESSEL SET IN SUDDEN ROTATION

A cylindrical reactor of material processing systems is sometimes rota ted about its axis or an offset axis in order to enhance mixing and ho mogenize temperature and chemical compositions. As a simplified model for this kind of flow field, a water bath contained in a cylindrical v essel suddenly set in rotation about its axis was taken up. The flow e stablishment time of the water flow in the bath, defined as a period t ill the instantaneous tangential velocity component exceeded 95% of it s final steady state value, was determined experimentally. Two differe nt boundary conditions were imposed on the top part of the bath. One w as covered with a flat circular disk and the other was free surface. T he flow establishment time thus determined was correlated as a functio n of the angular frequency of relation, the diameter and depth of the bath, and the kinematic viscosity of liquid. The existence of the top wall shortened the flow establishment time significantly.