3D-Flow Structures Behind Truncated Circular Cylinders

An experimental investigation of the two flows around finite circular cylinders with different head geometries mounted on a flat plate, see fig. 1, is reported. The aspect ratio L/D (with length L and diameter D) of both cylinder models is 2.0. The focus of this study is toward examining the complex separated flow structures and wake properties as well as the influence of the head geometry on the flow characteristics. Velocity and turbulence measurements have been carried out with a three component Laser Doppler anemometer (LDA) at the Reynolds number Re_D = 2.0 · 10⁵. The experimental results show complex 3D fluid motions in the regions of separated flow. They are induced by the superposition of three main vortical flows. The developing vortex and turbulence structures for both investigated models show similar overall features. Differences in the geometries of the 3D-envelopes of the recirculating flow as well as in the distributions of turbulent terms can be allocated to differences in the vortical flows over the free end surfaces of the cylinders.