Numerical Elucidation of Flow Characteristics Induced by Axial Clearance in a Rotating Disk

Rotating disks play a critical role in various engineering applications, including turbines, water wheels, and hard disk drives. Despite their importance, the influence of disk geometry—particularly axial gaps—on flow behavior has not been sufficiently explored. This study conducts numerical simulations to investigate vortex structures generated around a rotating disk with varying axial gaps. Flow fields are analyzed using the second invariant of the velocity gradient tensor (Q-criterion), and vortex transitions are examined across Reynolds numbers ranging from 2500 to 20000. Results show that smaller axial gaps promote laminar-like vortex behavior, while higher Reynolds numbers induce transitions toward spiral vortex structures. The findings provide insight into flow mechanisms influenced by disk geometry and contribute to improved understanding of rotating disk systems.