Experimental Characterization of Near Wall Structure in Rotating Turbulence

Turbulent flows in rotating systems play an important role in a variety of fields, including climate systems, ocean currents, etc. Compared to the geophysical applications, which are widely studied by most previous research, the near-wall structures and the effects of rotating-related forces (i.e., Coriolis force and centrifugal force) on boundary layers are unidentified. In this study, a new rotating platform is fabricated to achieve controllable rotating speed up to 55 rpm. The vibration of the rotation platform is minimized with machined alignment parts and a turntable bearing to avoid effects on turbulence. The flow features at different rotation numbers are investigated. The 3D flow structures are examined with an onboard 4-camera tomographic PIV system. The centrifugal force and Coriolis force introduce asymmetry in the main flow velocity and the Reynolds stress distribution. They also affect the length scale of the boundary layer as well as the eddy structures.