Turbulent mixing in non-isothermal jet in crossflow

Abstract

Large eddy simulation (LES) of turbulent mixing in a non-isothermal jet in crossflow (JICF) configuration is conducted with a hybrid Eulerian–Lagrangian mathematical/computational methodology. In this methodology, a high-order finite difference (FD) multi-block method is used to solve the Eulerian filtered Navier–Stokes equations in a generalized coordinate system. The composition field is described by the filtered mass density function (FMDF) and its equivalent stochastic Lagrangian equations, which are solved by a Lagrangian Monte Carlo (MC) method. The consistency of the Eulerian and Lagrangian parts of LES/FMDF is established for isothermal and non-isothermal JICFs. It is demonstrated that the instantaneous and averaged scalar concentration and temperature fields as obtained from LES-FD and FMDF-MC data are very similar. The LES/FMDF results are also in good agreement with the available experimental data, indicating the accuracy and reliability of LES/FMDF model. The numerical results show that the variation in temperature has a significant effect on the flow and mixing in JICF. By decreasing the jet to crossflow temperature ratio for fixed jet and crossflow velocities, the jet penetration, the spreading rate, the entrainment and the mixing are considerably improved.