Abstract
The effective viscosity νe and the effective diffusivity of bubbles De in a vertical bubbling jet in a cylindrical bath were determined from the governing equations based on the boundary layer approximation and the Boussinesq approximation. These approximations were satisfied in the buoyancy region in the vertical bubbling jet. Gas holdup and mean bubble rising velocity needed in calculations of νe and De were measured with a two-element electro-resistivity probe, and the mean velocity of water with a laser Doppler velocimeter. The values of νe and De were almost the same on the jet axis in the buoyancy region and increased with an increase in the injected gas flow rate. The radial profile of νe was parabolic and that of De was almost uniform across the bubbling jet. The profile of νe was different from the profile of νe in a single-phase turbulent free jet.
