Transition for lifting-up flow patterns along the outer surface of a rotating cone

When a cone is immersed in liquid with its top upside down and rotated, a phenomenon is observed in which liquid is lifted up over the outer surface of the cone. The lifting-up phenomenon is related to Rayleigh-Taylor instability, and is caused mainly by the balance between centrifugal force and viscous resistance. When the viscosity of the liquid is smaller, the fluid is lifted up like a filmwise across the entire cone surface, because the viscous resistance is smaller. On the other hand, when a fluid with high viscosity is used as the working fluid, the viscous resistance is larger and the liquid is not lifted up in a filmwise shape. In such a case, the development of disturbance waves generated on the surface of the cone causes the flow to be lifted up in a filamentwise shape due to spinnability. In this paper, we introduce the phenomena by flow visualization on the transition of the flow patterns between filmwise and filamentwise lifting-up. Furthermore, we report the change in the lifting-up flow patterns with viscosity change and its relationship to starting rotation rates for the lifting-up. Finally, we perform a dimensionless rearrangement from the experimental results and show a dimensionless correlation equation.