Modeling of turbulent opposed-jet mixing flows with κ̃–ϵ̃ model and second-order closure

A numerical model for turbulent opposed-jet mixing flows is developed with a one-dimensional (1-D) formulation with various turbulence models. Calculations with different combinations of turbulence and scalar models are conducted. The performances of various models are evaluated by extensive comparisons with existing experimental data. The numerical model is then used for studying the dependence of predicted scalar field on exit bulk velocity and turbulence intensity. Model results in general agree well with trends observed experimentally. The importance of non-zero velocity gradient at jet exit on the predicted results is illustrated through exploration runs. The distribution of mechanical-to-scalar time scale ratio, CD, is deduced from results obtained with a Reynolds stress model. The value of CD is found to deviate substantially from the commonly used value of 2, especially when the density variation is large.