01. Experimental/Computational Fluid Dynamics

The geometry and dynamics of co-rotating systems, such as turbomachinery, rotating machines, and hard disk drives (HDDs), play a crucial role in their efficiency related to fluid flow. These systems can experience long-term failures due to issues arising from fluid dynamics. In HDDs, for example, flow-induced vibrations occur not only because of the system's geometry and dynamics but also due to the movement of the arm from the shroud to the disk area. In our refractive index matched HDD model, the disk and arm are the primary rotating and moving components, respectively. The non-axisymmetric shrouded wall acts as a barrier to external atmospheric conditions by directing airflow, reducing turbulence, and managing pressure distribution. The rotating disks create centrifugal forces that drive the fluid radially outward, establishing a boundary layer and a pressure gradient, resulting in a complex airflow pattern. The arm interacts with this airflow, experiencing drag forces and contributing to the overall fluid velocity within the drive, particularly with the inflow from the shroud opening. This inflow exerts shear stress on the disk region, contributing to momentum exchange, especially due to the accelerated flow from the arm-hub region. Our two-dimensional average velocity results were revealed in Cartesian coordinates and analyzed in cylindrical coordinates. In this symposium, we intend to demonstrate the velocity and vorticity distributions, which showed irregular profiles resulting from the momentum exchange. Rigid body rotation around the hub varies according to regions with forced vortex regions existing within the flow. Moreover, in some regions of the flow, there are indications of secondary flow suspected to exist in the axial plane below the upper disk and above the lower disks, respectively.