Large eddy simulation of a high reynolds number turbulent jet in crossflow

Large eddy simulations (LES) are performed to study a turbulent jet issuing perpendicularly into a turbulent crossflow, where both jet and crossflow are at high Reynolds numbers. Dynamic Smagorinsky sub-grid scale eddy viscosity model is used. The numerical results show that the mean velocity and root mean square velocity in the near-field and far-field are in agreement with the experimental results. The iso-surface of instantaneous pressure at the upstream of jet-exit is orthogonal to the jet streamlines of mean velocity, which indicates that the upwind vortices are generated by the Kelvin Helmholtz shear layer instability. The constant number A and B of the jet trajectory in the Empirical formula based on the length scale RD given by Broadwell and Breidenthal are 1.35 and 0.3, respectively, by fitting the simulation results. The three-dimensional vortex structures are visualized and investigated by the streamlines of mean velocity, the average vorticity and the iso-surface of Q-criterion, respectively. The entrainment and rolling up of the crossflow fluid caused by the jet flow are observed respectively by the three-dimensional streamlines of mean velocity. Close to the wall, there is a pair of secondary vortices, rotating in the opposite direction of the counter-rotating vortex pair (CVP) characterized by the average vorticity. Due to the high Reynolds numbers of jet and crossflow, the vortex structures visualized by the Q-criterion, start to break down at about one fuel jet diameter downstream of the jet-exit.