Numerical Techniques for Steady Two-Dimensional Transcritical Stratified Flow Problems, with an Application to the Intermediate Field Dynamics of Ocean Thermal Energy Conversion Plants

摘要

The development of predictive techniques for the predominantly horizontal, layered fluid motions that result when a continuous buoyant source is discharged into an ambient fluid at a bounding surface, interface or equilibrium level is studied. Although the numerical techniques developed are applicable to general discharge configurations, the model development is focused on the particular case of a radial source of buoyancy and momentum discharged into a uniform ambient crossflow. The resulting density current is analyzed by application of the depth-integrated hydrodynamic equations. The density current dynamics are shown to vary with the relative intermediate- to near-field strengths, as characterized by the ratio of their respective length scales. The complete range of this interaction, from small near-field effects to large near-field effects, is investigated. Results are presented as the depth integrated velocity and current thickness distributions for different field strength values. The model predictions are compared to two sets of laboratory data and to limited field information, involving a river discharge and a submerged outfall into the ocean. Good agreement is obtained in all cases. Finally, the model results are applied to the prediction of a river plume into a coastal ocean current and to the continuous discharge from an OTEC plant operating in the stratified ocean. In both cases, the results indicate the significant horizontal extent (order of several kilometers) of the resulting current, together with their limited vertical extent (order of several meters). Their strong sensitivity to ambient current magnitude and stratification strength is demonstrated. (ERA citation 10:023653)