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Usually, the activation of DPF regeneration strategies is based on the estimation of the total particulate mass collected in the filter by means of the backpressure measure; no information concerning soot deposition profile on porous media is considered. In this paper, a numerical procedure is used to investigate the influence of soot profile on overheating during the regeneration process inside a commercial Diesel Particulate Filter. At first, the soot deposition profile, identified by a low number of parameters, is computed basing on the engine operative conditions. Then, the regeneration process is simulated. In this way, not only the amount of the total accumulated mass is taken into account, but the role of the shape of soot profile is accounted for. This allows to evaluate the correlation between the shape of collected particles layer and possible local overheating phenomena, which are very important to avoid critical thermal-structural stresses.

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.