Bubble Vortex Interaction within Cross Flow over a Cylinder

Vortex-induced vibration from cross flow over bluff bodies is an important design consideration in devices from flow meters to nuclear reactors. Under multiphase flow, changes in the shedding frequency and cylinder vibration amplitude have been observed; however, a satisfactory explanation for these effects does not yet exist in literature. In the present work, we combine experimental and numerical studies to span a larger bubble size range than is typical in literature (50-800 microns) across a Reynolds number range (based on the cylinder diameter) of 8500-25000. The motion of monodisperse bubbles is studied experimentally in 3D using tomographic bubble tracking; the flow field at the centerline plane is determined simultaneously with 2D-3C stereo PIV. The experimental results are used to validate a one-way coupled point-particle tracking model, for which the flow field is computed using high-order LES. Using the combined experimental and numerical data, trends in bubble vortex capture probability across the parameter envelope are identified. The time and spatially dependent forces leading to vortex capture are evaluated across normalized bubble trajectories, and estimates are made of the momentum coupling between the liquid and gas phase.