Summary of Two-Dimensional CFD Simulations for Modelling the Effects of Weather Conditions on Vehicle Aerodynamic Properties

The current automotive industry is undergoing structural changes. Sustainable vehicle components and environmentally friendly structures have become some of the most important parameters. To meet these demands, vehicles can be optimised in different ways. One of them is aerodynamic optimisation. Several weather conditions affect vehicles, including rain, wind, and air temperature. The effects of these parameters are less well studied, but based on previous investigations, they are essential to consider. The aim of the paper is to summarise the possibilities of CFD simulations for modelling weather-related factors. Three factors are examined: rain, wind, and air temperature. In case of precipitation, two different modelling methods are presented. One of them uses a multiphase flow simulation approach, while the other increases the average density of the air. Wind investigations were carried out using single- (side wind effect analysis) and multi-inlet settings (more complex wind effect study) with different angles of attack. The effect of temperature is examined over a wide range, from –20 to +40 °C, which covers the typical temperature conditions in Europe. The paper uses both theoretical knowledge and CFD results to identify and collect the most appropriate modelling methods. Based on the created simulation environment and calculated numerical results, limitations and necessary simplifications were defined. The paper summarises four main conclusions.