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This paper discusses flow through the front end of a vehicle comprising all the underhood/underbody components. Two approaches used to model the fan to predict the front-end airflow in a full vehicle model using Computational Fluid Dynamics (CFD) are presented. The approaches discussed here are the Moving Reference Frame (MRF) model and the fan plane model. Both cold and hot flow conditions are carried out for the full vehicle model. This paper also outlines the determination of fan performance curves numerically. The data from the fan performance curves thus obtained can be used in a fan plane model. The paper also discusses two methods to determine the recirculation factor in front-end flow studies namely, the user-defined scalar (UDS) method and the heat balance method.

This paper describes a Computational Fluid Dynamics (CFD) technique for evaluating the effectiveness of an intake manifold/ EGR system. The effectiveness of the intake manifold is defined in terms of equal distribution of EGR to individual cylinders. The procedure described in this work is unparalleled, since the available testing techniques are inadequate to make measurements of the actual EGR distribution. This paper also outlines a 1D - 3D coupling approach to apply transient boundary conditions on the CFD model. As part of this study, the development of an intake manifold/ EGR system is described under different operating conditions. Different intake manifold designs are also compared. Various parameters affecting the distribution of the EGR are discussed.