Abstract
This paper describes the bubble plumes along a wall surface. Experimentson the bubble plumes were systematially performed and thereafter, we analize the behavior of the bubble plume, using the following assumptions. As previously reported, the interference diffusion coefficient varies only in vertical direction, as a function of bubble density at the center of the plume. The bubbles have a constant velocity relative to the surrounding water in a plume. Wall friction velocity Ux is defined by Ux2=CfUo2/2 and skin friction coefficient cf has a constant value. The eddy diffusivity is epxressed as the product of representaive mean velocity and width of bubble plumes. On the basis of the above assumptions, moment method is applicable for analysis. By the comparisons of the theory and the experiments, the coefficients of skin friction, interference diffusivity and eddy diffusivity were evaluated. By measurements of turbulence in bubble plumes, the turbulent intensity distribution has a peak near the point of the half width of velocity profile. Inertial subranges are found in the energy spectra of the velocity fluctuations.
