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Demands for higher power engines have led to higher pressures in fuel injectors. Internal nozzle flow plays a critical role in the near nozzle flow and subsequent spray pattern. The internal flow becomes more difficult to model when the injector pressure and internal shape make it more prone to cavitation. Two Bosch injectors, proposed for experimental and computational studies under the Engine Combustion Network (namely “Spray C” and “Spray D”) are modeled in the computational fluid dynamics code ANSYS Fluent. Both injectors operate with n-dodecane as fuel at 150 MPa inlet pressures. The computational model includes cavitation effects to characterize any cavitating regions. Including compressibility of both liquid and vapor is found to be critical. Also, due to high velocity gradients and stresses in the nozzle, turbulent viscous energy dissipation is considered along with pressure work resulting from significant pressure changes in the injector.

A transient, 3-dimensional, continuum CFD model of soot loading and regeneration has been developed for a single channel unit in a diesel particulate filter. The detailed model is used to predict the soot loading, velocity, temperature, and species distributions in both the air channels and porous walls of the filter. The simulation is performed in two phases: loading and regeneration. In the loading phase, soot profiles are estimated for a clean filter using a steady-state simulation. In the second phase, transient regeneration is modeled using a single-step, irreversible heterogeneous mechanism is used to predict the formation of carbon monoxide and carbon dioxide products during the regeneration process, incorporating a fractionization scheme. Reaction rates are predicted via an Arrhenius rate law, but may be tempered due to diffusion-limiting conditions in the porous reaction zone. Simulations are performed with a commercial CFD package and user-defined functions.