非軸対称容器内で積層回転円盤に駆動される流れに関する不変量に基づく流れ構造解析の試み

抄録

We focus on complex flow existing in hard disk drive used as information storage device. Fast revolution of thin disks drive the fluid inside an enclosure. The resulting rotating flow passes through complex geometry inside the drive and hence the flow exhibits unsteady three-dimensional behavior. In the past research, we have observed the behavior using flow visualization, and the velocity statistics have been obtained based on particle image velocimetry (PIV). However, some of the statistics are coordinate-dependent and their interpretation remains difficult. In the present study, we attempt topological understanding of the flow stuructures based on tensor invariants. We calculated two-dimensional invariant maps of flow velocities obtained by two-dimensional PIV measurements. In the topological analysis, we found out that there is a certain implication of the instable states on a quadrant region with disturbance by the insertion of an arm into the rotating flow.