Behavior of immiscible two liquid layers contained in cylindrical vessel suddenly set in rotation

Immiscible silicone oil and water were contained in a cylindrical vessel, The ratio of their volumes, referred to as the volume ratio, was varied over a wide range. The vessel was suddenly set in rotation, and the flow velocities of the two liquids were measured with particle image velocimetry (PIV) and laser Doppler velocimetry (LDV). The flow establishment time was defined as the period from the start of rotation to the moment at which a steady state is established in the vessel. An empirical equation for the flow establishment time was proposed as a function of the volume ratio, the angular frequency of rotation, and the physical properties of the liquids. The deformation of the silicone oil-water interface was also observed to confirm the findings obtained from the velocity measurements.