Bubble plumes and the Coanda effect

This paper experimentally describes the behaviour of a gas-liquid bubble plume set to develop adjacent to another plume. When this happens, the plume exhibits a type of a Coanda effect, bending towards the other plume. The local gas fraction measurements are carried out using the electro-resistivity probe technique in an air-water system. The deflection angle of the plumes is shown to present a logarithmic dependence on the modified Weber and Froude numbers of the flow. In addition, a simple theory based on integral methods is advanced for the prediction of the plume deflection; the theory considers a variable entrainment coefficient.