Large-eddy Simulation of the Near-lip of a Jet

A M=0.6, Re=1.0 million cold jet flow with complex geometry is simulated to obtain high-fidelity near-field data and accurate dynamic information on the flow. Large Eddy Simulation (LES) on an unstructured grid is optimal for near-nozzle flow simulation. The modeled problem is a single-stream jet exiting a nozzle which can have tabs. It is too costly to simulate the full problem so the meshed domain is a representative sector of the flow with limited stream-wise extent. The jet flow is simulated using a stable, accurate, finite element method with hierarchic spatial basis, generalized-alpha method and 2nd order time integrator which yields accurate well controlled stabilization. A RANS solution is used as the inflow condition where velocity and temperature are specified for the jet and the entrainment. As RANS only gives averaged quantities the inflow boundary condition needs to be completed by specifying the fluctuations using scaled plane extraction boundary condition (SPEBC). The solution is rescaled from an internal downstream position using self-similarity flow profiles in turbulent boundary layers. This talk will show the need for SPEBC and present preliminary results.