Unsteady Spread of Buoyant Surface Discharge

A study is made of the spread which results from the discharge of a buoyant effluent at the free surface. Similitude is applied to develop functional equations for rate of spread, concentration, and shape, and experimental data are given for the rate of spread. Previously published data are used to demonstrate the validity of the other derived equations and to show how comprehensive mixing diagrams can be prepared by logical experimentation. Methods of choosing scales for hydraulic models are considered. Also shown is how the effect of viscous influence limits the available choice.