Study of Reynolds Stress Equation for Prediction of Flow Characteristics of Free Jet.

This report concerns the prediction of the flow characteristics of an isothermal free jet. A computer program has been developed. Reynolds stress equations are used so that not only turbulent shearing stress, but also turbulent kinetic energy and dissipation can be calculated. This program is rather short, about 280 statements, and for a moderate number of points usually about 15, requires only five seconds per run for the Amdahl 470V6 computer. The results compare fairly well with experiments in two-dimensional as well as in axi-symmetric jets. It is found that the similarity assumption is only approximate. Also the results can be somewhat different for different initial input turbulence conditions. Therefore, comparison of experimental results and interpretation of their accuracy, particularly when no detailed measurements are made at the jet orifice, should be done cautiously. The variations due to the assigned constants in the closure model are also briefly discussed.