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In the present work we investigated experimentally and computationally the unsteady flow around a BMW car model including wheels*. This simulation yields mean flow and turbulence fields, enabling the study aerodynamic coefficients (drag and lift coefficients, three-dimensional/spatial wall-pressure distribution) as well as some unsteady flow phenomena in the car wake (analysis of the vortex shedding frequency). Comparisons with experimental findings are presented. The computational approach used is based on solving the complete transient Reynolds-Averaged Navier-Stokes (TRANS) equations. Special attention is devoted to turbulence modelling and the near-wall treatment of turbulence. The flow calculations were performed using a robust, eddy-viscosity-based ζ - ƒ turbulence model in the framework of the elliptic relaxation concept and in conjunction with the universal wall treatment, combining integration up to the wall and wall functions.

The potential of single-point turbulence closure models for predicting the flow aerodynamics and turbulence in internal combustion engines (IC) was investigated by computational study of idealized valveless piston/cylinder configurations. The main flow cases considered are the swirling flow in a single stroke rapid compression machine (RCM) with flat and bowl-shaped cylinder head, as well as cyclic compression. Although still remote from a real engine, these configurations enable to analyse joint effects of major phenomena governing the aerodynamics in IC engines: shear, separation, swirl and compression/expansion. Prior to the computation of these engine-like flows, an extensive validation of applied turbulence models was performed in homogeneous and wall bounded shear flows, each featuring separately rotation, swirl and mean flow compression effects.