Large Eddy Simulations of high pressure jets: Effect of subgrid scale modeling

Abstract

The focus of this study is on developing high-fidelity models and simulations for fully turbulent high-pressure flows. To this end, two Large Eddy Simulation (LES) models are considered and simulations are conducted with these models for initial conditions for which experimental data is available. In the first LES, denoted as Standard LES (SLES), the only subgrid-scale (SGS) model used is that stemming from the convective terms of the conservation equations. In the second LES, a complementary SGS model for the difference between the gradient of the filtered pressure and the gradient of the pressure computed as a function of the filtered flow field is used in the momentum equation additional to the SGS model employed in SLES; this second model is labeled PLES. The comparison of the SLES results with experimental data is favorable, however, PLES visibly enhances the accuracy of the results compared to the same data. A detailed analysis reveals that in PLES the dense-fluid core persists further downstream than in SLES, unsteadiness is increased, and mixing is enhanced further downstream. The differences between PLES and SLES occur in a narrow radial ring of radius three jet diameters around the jet, although they persist at large distances downstream from the inflow. It is recommended that details experimental data should be obtained in this elongated ring region in order to more completely evaluate the potential of PLES compared to SLES.