A pdf Description of Turbulent Axisymmetric Free Jet Flow

This study presents the application of a turbulence probability density function (pdf) equation to compute an a.visymmetric turbulent free jet flow. In view of the difficulty of solving {his pdf equation directly by conventional numerical methods, an approximate moment method is applied. The calculated triple velocity correlations appearing in the second-order moments equation are calculated and compared with measured values and with those estimated by moment-closure models. The results reveal that the pdf approach gives consistency in the higher-order moments and radial budget of third moments of velocity, and that the neglect of {he mean-strain production, the rapid part of the pressure correlation and the dissipation are responsible for deviations between moment-closure models and experiments. Therefore, pdf methods appear lo be more suitable than conventional moment-closure models in terms of revealing turbulence structure.