Impact of bubble size on turbulent statistics in bubble plumes in unstratified quiescent water

We report an experimental investigation of turbulence in bubble plumes released unstratified quiescent water. The focus is to study the detailed turbulent statistics and budget terms equations kinetic energy (TKE), particularly about their distributions radial direction compared those single-phase momentum jets buoyant plumes. Two types diffusers were used generate consisting different sizes population at same source gas discharge. have growth behaviors under combination population: with many small bubbles show decreasing centerline velocities along vertical direction; larger but fewer a tighter core, smaller spreading ratio, almost constant velocities. ratio turbulence-to-mean flux strongly affected by population, demonstrated profiles normalized velocity correlations using mean flow parameterizations. Velocity fluctuations strong vertical-to-horizontal anisotropy Strong fluctuating component contributes significant role re-shaping stresses transport when plume composed bubbles. Local balance cannot be established equation TKE traditionally for flows. A bubble-related term governing needed close budget. An empirical drag force slip validated closure. provide diagram illustrate pathway direction, magnitude each influenced characteristics.