Flow Near a Rotating Disk

Abstract

Flow near a rotating disk with constant angular velocity is a typical example of a three dimensional boundary-layer flows. In the case where the flow around a disk is rotating in a housing, i.e., when the rotating disk is enclosed, we can apply the flow model of a turbo-machinery impeller in a casing to estimate the frictional torque. Thus, many studies have been performed to clarify the characteristics of such flow. In this chapter, experiments were carried out to measure the velocity profile and frictional torque acting on a rotating disk with fluid slip in a Newtonian fluid filled chamber. A disk with a highly water-repellent wall gave rise to the drag reduction phenomenon when the moment coefficient was in the laminar flow range. Analysis of the moment coefficient by using momentum integral equations with the fluid slip boundary condition revealed results that qualitatively agreed with the experimental results.

Keywords: Drag reduction, rotating disk, frictional torque, boundary layer flow, Couette flow, highly water-repellent wall, fluid slip, momentum integral equation, moment coefficient, sliding constant, flow angle.