The electric vehicle revolution has transformed the automotive industry into one that prioritises efficiency, lightness, and low-cost. Innovation has become a key cost in automotive companies, where in Europe in 2020, €58.8 billion was invested in Research & Development (Hatton, 2022). Computer simulations have been emerging as a cost-effective and reliable method in early vehicle conceptual development (Dhaubhadel, 1996). In the area of aerodynamics, Computational Fluid Dynamics (CFD) can be a pre-test bed for novel design concepts before wind tunnel validation (Ding et al., 2006). Typically, a separated wake flow forms at the back of the vehicle, which has a significant impact on its fuel efficiency and drag (Velshankar, Senthilkumar & Kannan, 2019). Therefore, the employed solving method must be able to predict air flow behaviour in this recirculation region and is crucial to the accuracy of the results. An accurate simulation model can minimise the cost of unnecessary wind-tunnel testing and speed up the rate of development. The benefit of a combination of the Reynolds Averaged Navier-Stokes (RANS) and the Large Eddy Simulation (LES), namely Detached Eddy Simulation (DES) is determined in this study. DES has been used for performance car aerodynamic simulations by companies such as Koenigsegg in their Jesko hypercar (Hatton, 2022). An investigation to the sensitivity of y+ values to accuracy has been completed in tandem with an implementation of Improved Delayed DES (IDDES) due to its wall modelling capabilities. While it has been shown that Y+ optimisation did not improve the prediction of the velocity in the recirculation region, it is hypothesised that a change in method to a Hybrid RANS-LES method to be more beneficial for this case of external flow around a moving body, which will be investigated in a continuation to this study.
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Zheng Wei, Kuek
Rights Holders: Zheng Wei, Kuek Supervisors: Mahak, M
Faculty of Technology, Design and Environment
MSc Motorsport Engineering
2022
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