| Jets in crossflow are central to a variety of applications such as fuel injection, gas turbine combustion and film-cooling. Direct Numerical Simulations are used to study the different aspects of round jets in a crossflow. The first problem studies the effect of jet and crossflow velocity profiles on jet trajectories and the near-field. A new scaling law for the jet trajectory is proposed, that accounts for these parameters. The proposed scaling is shown to be a significant improvement over current scaling laws.; DNS of a turbulent jet in crossflow is performed at conditions corresponding to an experiment (Su & Mungal 2004). Detailed comparison shows good agreement with experiment, and additional quantities, not available experimentally, are presented. Turbulent kinetic energy budget is computed, and is used to suggest possible reasons for the difficulty experienced by current engineering models in predicting this complex flow.; A predictor-corrector approach is implemented to compute passive scalar transport. This ensures that the local scalar concentration is always within bounds. The passive scalar is introduced along with the jet fluid, once the velocity field is statistically stationary. Mean scalar profiles show a good agreement when compared to the experiment. The scalar field is used to compute entrainment of the crossflow fluid by the jet, which is greater than that in a regular jet. The reasons for a transverse jet's enhanced entrainment are explained in terms of the pressure field in the vicinity of the jet.; A two-dimensional model problem is used to study jet cross-section deformation. The model jet deforms at its trailing edge, exhibits the Kelvin-Helmholtz instability at its outer edges, and---later---yields a counter-rotating vortex pair (CVP). The model jet experiences constant acceleration in its initial stages, and moves at constant velocity at longer times. Deformation of the jet cross-section may be explained in terms of the pressure field that the crossflow fluid imposes on the jet, and the acceleration that the jet experiences. It is shown that the CVP is formed even in two dimensions, and that the pipe is not necessary. |
