Author(s): Masamitsu Arita; Gerhard H. Jirka; Nobuyuki Tamai
Abstract: On the basis of flow force conservation the two-dimensional buoyant surface discharge of a light fluid over a stagnant ambient fluid can be classified into four regimes: a fully entraining buoyant jet, a jet/jump combination, a direct jump, or a flooded jump. A depth-discharge diagram for such entraining flows is presented to assess these different transition paths between a supercritical discharge and an imposed subcritical downstream condition. Certain flow instabilities are predicted to occur at downstream Froude numbers of 1 or 1/2, respectively. Comparison with various experimental data, including additional data by the authors, confirms the flow force conservation theory. Furthermore, a more detailed analysis of the spatial development of a buoyant surface jet is made using an entrainment formulation with buoyant damping for closure of the governing equation. The predictions compare favourably with experimental data.