Multidimensional models to predict fuel behavior in an intake port-injection gasoline engine are explained. The discrete droplet model (DDM) is widely used for engine fuel simulations. The DDM is a kind of Lagrangian particle model and extended to apply to gasoline engines. Recent progresses in the submodels of the DDM, which are atomization, wall impingement, wall film flow, multicomponent vaporization models and so on, are introduced. The limitations of such these models are commented. Although there are only a few applications to a real engine, a report on the validations of the fuel behavior models is introduced. Because of a lot of port-wall-wetting fuel, it is difficult to predict the in-cylinder mixture distribution via one cycle single fuel injection calculation. However, the calculation of the fuel behavior in the intake port is practically usable to analize the injected fuel wetting.
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