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In two stroke engines, the scavenging process has direct influence in the performance of combustion process and then retains great importance in the strategies oriented towards solutions characterized by improvements of fuel efficiency, engine power output and reductions of pollutant emissions. The authors have developed an integrated numerical-experimental predictive tool, based on a two-step procedure, in which zero-dimensional, one-dimensional and three-dimensional simulation models are applied. In this paper, the attention is focused on the analysis in detail of different flow patterns which contribute to determine the scavenging process in order to provide a better comprehension and then to get improvement of such complex process. Since the scavenging efficiency strongly depends on the geometry of the engine system, the effect of a variation of the geometrical parameters on the flow paths and on the distribution of the scavenge streams is investigated.

Concerns about the harmful exhaust emissions of internal combustion engines have imposed the employment of aftertreatment devices to reduce their impacts both on health and environment. System modeling of engine and aftertreatment devices is required not only to provide an accurate assessment of the engine and aftertreatment devices performances as single elements but also to quantify the complex interaction of these components from a thermo fluid perspective. The work focuses on development of a model capable of predicting temporal and spatial evolution of thermo-fluid quantities and chemical species in a diesel oxidation catalyst (DOC). The developed model allows to investigate the influence of thermal characteristics and gas composition on the evolution of the phenomena occurring in the device which deeply reflect on the particulate filter behavior during regeneration phase.