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This report presents an evaluation of the papers presented during the AGARD Fluid Dynamics Panel Symposium on Fluid Dynamics of Jets with Applications to V/STOL held 2-5 November in Lisbon, Portugal. General observations on progress in the understanding of the flow phenomena associated with jets are followed by more specific comments related to the five topical sessions of the meeting: Jet Interactions with Neighboring Surfaces, Jet Structure and Development; Windtunnel Simulation of Flow Field, Forces Moments; Injection and Thrust Augmentation; and Theoretical Models and their Assessment. Conclusions and recommendations for further work drawn from the presentations and discussions at the Symposium are included.

We present new, third-epoch HST H-alpha and [S II] images of three HH jets (HH 1 and 2, HH 34, and HH 47) and compare these images with those from the previous epochs. The high-spatial resolution, coupled with a time-series whose cadence is of order both the hydrodynamical and radiative cooling timescales of the flow allows us to follow the hydrodynamical/magnetohydrodynamical evolution of an astrophysical plasma system in which ionization and radiative cooling play significant roles. Cooling zones behind the shocks are resolved, so it is possible to identify which way material flows through a given shock wave. The images show that heterogeneity is paramount in these jets, with clumps dominating the morphologies of both bow shocks and their Mach disks. This clumpiness exists on scales smaller than the jet widths and determines the behavior of many of the features in the jets. Evidence also exists for considerable shear as jets interact with their surrounding molecular clouds, and in several cases we observe shock waves as they form and fade where material emerges from the source and as it proceeds along the beam of the jet. Fine-structure within two extended bow shocks may result from Mach stems that form at the intersection points of oblique shocks within these clumpy objects. Taken together, these observations represent the most significant foray thus far into the time domain for stellar jets, and comprise one of the richest data sets in existence for comparing the behavior of a complex astrophysical plasma flows with numerical simulations and laboratory experiments.

A study was conducted to evaluate the accuracy of a commercial computational fluid dynamics (CFD) code (CFDRC-ACE+) for predicting incompressible air jet flows with simple geometries. Specifically, the axis-symmetric and two-dimensional heated air-jets were simulated using a standard k-epsilon turbulence model. These CFD predictions were directly compared to an extensive compilation of experimental data from archive literature. The round jet results indicated that the code over-predicted the velocity-spreading rate by 24% and the temperature spreading rate by 29%.

The Symposium on Fluid Dynamics of Jets with Applications to V/STOL was planned in response to current aeronautical developments which highlight the need for improvements in the understanding of jets and the fundamentals of mixing. The most important of these developments are vertical and short take-off and landing aircraft which employ thrust vectoring or lift augmentation. Sessions on Jet Interactions with Neighbouring Surfaces, Jet Structure and Development, Wind Tunnel Simulation, Injection and Thrust Augmentation, and Theoretical Models provided a comprehensive overview of the state of the art in the field.

A study was conducted to evaluate the accuracy of a commercial computational fluid dynamics (CFD) code (CFDRC-ACE+) for predicting incompressible air jet flows with simple geometries. Specifically, the axis- symmetric and two-dimensional heated air-jets were simulated using a standard k- epsilon turbulence model. These CFD predictions were directly compared to an extensive compilation of experimental data from archive literature. The round jet results indicated that the code over-predicted the velocity-spreading rate by 24% and the temperature spreading rate by 29%