A model for the injection boundary conditions in the context of 3D simulation of Diesel Spray: Methodology and validation

Downstream Inflow Turbulent Boundary Conditions (DITurBC) are presented for the Eulerian–Eulerian Large Eddy Simulation (LES) or Reynolds Average Navier–Stokes (RANS) simulation of Diesel Sprays. These boundary conditions initiate the spray physics close to the nozzle exit, which avoids the difficulties linked to the 3D simulation of cavitation, primary break-up and turbulence in the near-nozzle region. An injector model is combined with mass and axial momentum conservation equations to obtain mean profiles of velocity, volume fraction and droplet diameter at a given distance downstream from the nozzle exit. In order to take into account the unsteadiness of the flow, velocity fluctuations are added to the mean profile. These boundary conditions are assessed by comparison with existing data on injection velocity, spray angle and velocity profiles from numerous experiments.