ASSESSMENT OF THE SSG PRESSURE-STRAIN MODEL IN FREE TURBULENT JETS WITH AND WITHOUT SWIRL

Data from free turbulent jets both with and without swirl are used to assess the performance of the pressure-strain model of Speziale, Sarka r and Gatski, which is quadratic in the Reynolds stresses. Comparative predictions are also obtained with the two versions of the Launder, R eece and Rodi model, which are linear in the same terms. All models ar e used as part of a complete second-order closure based on the solutio n of differential transport equations for each nonzero component of <( u(i)u(j))over bar> together with an equation for the scalar energy dis sipation rate. For nonswirling jets, the quadratic model underestimate s the measured spreading rare of the plane jet but yields a better pre diction for the axisymmetric case without resolving the plane jet/roun d jet anomaly. For the swirling axisymmetric jet, the same model accur ately reproduces the effects of swirl on both the mean flow and the tu rbulence structure in sharp contrast with the linear models which yiel d results that are in serious error. The reasons for these differences are discussed.