Bubble plume dynamics in a stratified medium and the implications for water quality amelioration in lakes

Abstract

The behavior of a bubble plume discharging vertically into a stably stratified water column is described using a simple one‐dimensional plume model. It is confirmed that the behavior can be described with just two dimensionless groupings, C and M, representative of the strength of the stratification and the discharge momentum. Depending on the values of these parameters, the plume can either extend the full depth of the water column or eject water at one or more internal detrainment points. The occurrence of these internal detrainment points can be described in terms of the relative magnitudes of the terms comprising the buoyancy conservation equation. Further, these internal detrainment points can be linked to both the mechanical efficiency and mixing effectiveness of bubble plumes. This is of importance when the bubble plume is being used to act as a destratification device in a lake. Generally, an integral number of internal detrainment points correspond to peak mechanical efficiencies. Maximum mixing effectiveness is favored by lower values of the stratification parameter C and higher values of the source strength parameter M.