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The paper is focused on the influence of the eddy viscosity turbulence models (EVM) in CFD three-dimensional simulations of steady turbulent engine intake flows in order to assess their reliability in predicting the discharge coefficient. Results have been analyzed by means of the comparison with experimental measurements at the steady flow bench. High Reynolds linear and non-linear and RNG k-ε models have been used for simulation, revealing the strong influence of both the constitutive relation and the ε-equation formulation on the obtained results, while limits in the applicability of more sophisticated near-wall approaches are briefly discussed in the paper. Due to the extreme complexity of typical ICE flows and geometries, the analysis of the behavior of EVM turbulence models has been subsequently applied to a test-case available in literature, i.e. a high-Reynolds compressible flow over a inclined backward facing step (BFS).

The evaluation of the steady-flow discharge coefficient of ICE port assemble is known to be very sensitive to the capability of the turbulence sub-models in capturing the boundary layer dynamics. Despite the fact that the intrinsically unsteady phenomena related to flow separation claim for LES approach, the present paper aims to demonstrate that RANS simulation can provide reliable design-oriented results by using low-Reynolds cubic k-ε turbulence models. Different engine intake port assemblies and pressure drops have been simulated by using the CFD STAR-CD code and numerical results have been compared versus experiments in terms of both global parameters, i.e. the discharge coefficient, and local parameters, by means of static pressure measurements along the intake port just upstream of the valve seat. Computations have been performed by comparing two turbulence models: Low-Reynolds cubic k-ε and High-Reynolds cubic k-ε.