Boosting Performance: CFD in the Automotive Universe

CFD Streamlines


CFD in Motorsport




In the 19th century, the Navier-Stokes equations paved the way for the mathematical description of complex fluid flow patterns. However, it was only with the advent of computer technology in the second half of the 20th century that it became possible to unravel this vast system of equations.


Computational Fluid Dynamics (CFD) has emerged as a vital branch of computer-aided processes and finite element methods. Focusing on the interactions between the fluid and its environment, CFD has become an essential tool for analyzing and optimizing fluid dynamic behavior in various applications.


As Computational Fluid Dynamics (CFD) made the transition from the aerospace industry to the automotive industry, it found a fertile ground for its application. In the 1990s, two-dimensional flow simulations were already being utilized by Formula 1 teams to enhance the profiles of rear wing elements. With the advancement of computational resources, CFD gained prominence in Formula 1, now boasting over 100 dedicated engineers working collaboratively with designers and aerodynamicists to improve the performance of racing cars.


The impact of CFD is not limited to Formula 1. Its presence is notable throughout the automotive landscape, being an indispensable tool in the development of race cars. In competitions such as NASCAR and Stock Car, where aerodynamics play a crucial role in performance and lap times, CFD has become an essential ally in the pursuit of efficiency and speed.


Simulation Process in Motorsports


Max Verstappen (NED) Redbull Racing RB18 during Formula 1 Italian Grand Prix in Monza ITA, Sept 14 2022
Max Verstappen (NED) Redbull Racing RB18 durante o Grande Prêmio da Itália de Fórmula 1 em Monza ITA, 14 de setembro de 2022


In the design of race cars, CFD analysis aim to accurately replicate real-life situations unfolding in the dynamic world of automotive racing. From straight-line acceleration to high and low-speed turns, overtaking maneuvers, and pursuits, each aspect is meticulously analyzed through the power of computational fluid dynamics.


The CFD simulation process for a race car is divided into three phases: Pre-processing, Solution, and Post-processing. In the pre-processing stage, the vehicle’s CAD is prepared for simulations, including mesh generation, as well as the configuration of flow characteristics and fluid properties. The solution phase is initiated, during which the simulation is executed according to the previously defined modeling, including turbulence models. Post-processing involves the analysis and preparation of data generated after the simulation, with Tecplot360EX being an essential tool for visualizing this data.


Differently from physical tests, the advantage of the CFD process lies in eliminating the need to produce complex prototypes or resort to wind tunnel models. This not only represents a significant cost-saving but also streamlines the development time.


Furthermore, simulation offers a unique perspective on results. While wind tunnel tests provide only the quantities recorded during the test, such as vehicle forces, CFD provides a complete view of the flow field. This empowers engineers to understand what happens within the flow field around the car and why these phenomena occur. This capability is crucial for the complex aerodynamics of modern cars, which extensively exploit vortex structures and flow topology to generate downforce efficiently.


ATS in Stock Car


CFD Streamlines


In the scenario of Stock Car competitions in Brazil, where the national category grows every year, performance analysis driven by ATS collaboration stands out. The CIMED team sought ATS expertise for an aerodynamic study of their car in the 2018 season, using renowned software in the market, consolidating ATS as a pioneer in such applications in Brazil.


CFD++ was essential in simulating the airflow around the car, standing out for its ability to handle complex geometries. The choice of ATS was based on its efficient integration with other software.


The visualization of the simulation results took place through Tecplot360EX. This software allowed ATS to effectively analyze the information generated by CFD++, providing valuable insights into the airflow behavior and aerodynamics of the car.


Ennova Mesh Generation:
The Ennova Mesh Generation was fundamental in developing the computational mesh over the three-dimensional model of the car. This tool enabled the creation of a mesh with 62 million elements, encompassing precise details of the car’s geometry. The effective integration between CFD++ and Ennova allowed ATS to accomplish the task in record time, even with complex geometries.


CFD Pressure Coefficent Stock Car
Coeficiente de Pressão


Based on the CFD++ model, the fluid dynamics related to the car were reconstructed based on specific boundary conditions. In the software interface, the car design was adjusted to replicate the same test conditions, allowing for a quantitative study of the design and its impact on aerodynamics. With the defined conditions, it became possible to describe the different pressure profiles acting on the car accurately, identifying potential aerodynamic flaws and suggesting improvements.


Velocity Fields


Considering the fluid velocity around the car as crucial for the aerodynamic study, streamlines were traced on the body to obtain a velocity profile. The first three illustrate the airflow streamlines, while the last provides a quantitative description of different fluid velocity profiles around the car. The analysis extended to identifying pressure profiles on the spoiler.


Coeficiente de Pressão no Spoiler


From these profiles, a performance analysis was conducted in terms of time gain in a real race scenario. Considering the changes suggested by the study for the team’s benefit in brake and curve zones, the positive time gain was 0.05s, while in the straight sections of the circuit, the gain was 0.08s.


Following ATS suggestions based on the presented study, Stock Car experienced the benefits on the track. Drivers achieved significant time results, and some obtained better rankings precisely due to the changes suggested by ATS through the CFD study.


Watch the video about our CFD work in Stock Car.


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