Examination of Secondary-Flow Structures formed by Corotating Disks using Reproduction Method of Three-Dimensional Velocity Fields based on Multiple Planar Velocities

Rotating flows driven by rotating disks exhibit complex three-dimensional structure in closed enclosure. The structure is caused by the secondary flow formed by centrifugal forces near the surface of the rotating disk. However, the details are yet to be known especially in non-axisymmetric enclosure and with an obstacle. In the present study, we focus on the flow in a hard disk drive (HDD) as a model. We investigate the structure of the secondary flow formed in the rotating flow between two parallel disks sharing a central axis in a non-axisymmetric container. Although PIV can measure the flow in the parallel disk cross section, the direct measurement of the axial flow remains difficult. Therefore, the axial velocities were reconstructed by applying mass conservation from the in-plane velocity distributions at different axial heights. We considered a more reliable reconstruction by modifying the calculation scheme. In the process, we utilized higher-order finite difference methods and numerical integrations to examine the effect of increasing the number of intervals and the effect of overlapping of the PIV measurement planes.