Industrial Application of an Advanced Elliptic- Blending Turbulence Model for Wheels Aerodynamics Analysis

The recent Worldwide Harmonized Light Vehicles Test Procedure (WLTP) requirements have introduced additional challenges in the car development phase. Continuous demand for environmentally friendly road vehicles has lead all OEMs to minutely investigate any potential feature that could reduce C02 emissions. Comprehension of the aerodynamics of wheels, which are one of the least explored areas, can bring novel solutions for future car designs. As the capacity of experimental facilities is limited, the need for reliable CFD methods has become crucially important. Although computational resources are continuously growing, the number of CFD simulations is increasing even faster. Professionally supported CFD process based on open-source technology has recently become an appealing alternative to commercial codes. The present paper describes a promising industrially-tested steady Reynolds Averaged Navier Stokes (RANS) approach which uses the elliptic-blending k-epsilon-zeta-f (ζ − f) turbulence model [1] along with the Compound Wall Treatment [2]. The superiority of ζ − f over any other first-order RANS models resides in its capability to capture some of the near-wall anisotropic effects without any recourse to complex tailored damping functions, like in realizable k-epsilon (RKE), which are usually only valid for a defined range of flow problems. CFD optimization of the wheels in a short development cycle is described. Extensive validation of the method is presented on a set of different wheel designs with modular rims for which experimental full-scale wind tunnel data, measured in moving ground conditions, are available. Further insight into correlation of experimental static pressure from pressure strips and drag coefficient is discussed as well as relevant flow field from numerical simulations is introduced.