Laboratory and Numerical Experiments Supporting the Improvement of Vortex Predictions in the Fastwake Numerical Code and Studies of Velocity in Stratified Turbulence

摘要

This report documents the results of ONR Contract N00014-99-C-0169. Three tasks were performed on this contract. The first task was to determine, through laboratory experiments and numerical simulations, how a vortex pair detrains fluid as a function of time. The motivation for this study was to determine how the fluid in a migrating vortex cell changes as the vortex pair migrates through the fluid. This study was performed in order to allow SAIC to compare predictions from the FASTWAKE code to experimental measurements. In the experimental part of the study, a vortex pair was generated by a lifting wing, and the detrainment of fluid from the vortex cell was determined for different values of Froude number. These results were then simulated with a 3-D numerical code. The results from this task are presented in Section 2. The second task in this contract was to determine the existence of oceanographic data that might be useful in understanding the results of a previous study. The results of this task are presented in a separate document (Lai and Delisi, 2005). The third task in this contract was to numerically model the turbulent flow behind a grid. The motivation for this study was to compare the flow behind a grid from experimental measurements to predictions from numerical simulations, in order to determine whether the numerical model could be useful in elucidating the physics in experimental measurements that were obtained far downstream of the grid. The results from this task, as well as corresponding measurements from a complementary laboratory experiment, are presented in Section 3.