2 CFD Tools

When it comes to automotive design, there are a variety of CFD tools available that differ in terms of accuracy, speed, cost, and usability. ANSYS Fluent is a comprehensive and versatile CFD software that can handle a range of flow regimes, turbulence models, mesh types, and multiphysics interactions. It is suitable for both steady-state and transient simulations and can be integrated with other ANSYS products for structural, thermal, and acoustic analysis. OpenFOAM is an open-source and free CFD software that can handle complex geometries, meshing, solvers, and post-processing; however, it requires more programming skills and user input than other CFD tools. SimScale is a cloud-based and user-friendly CFD platform that offers various simulation features such as incompressible and compressible flows, laminar and turbulent flows, heat transfer, multiphase flows, and rotating zones. Moreover, SimScale provides online tutorials, webinars, and support for beginners and experts alike.

3 CFD Methods

CFD methods are mathematical approaches and algorithms used to solve the governing equations of fluid flow. These methods can be divided into three categories: finite volume method (FVM), finite element method (FEM), and finite difference method (FDM). FVM is the most common and robust method, as it can handle complex geometries, unstructured meshes, and nonlinear problems. FEM is more suitable for problems involving elasticity, stress, and deformation, but can also be used for fluid flow with some modifications. FDM is the simplest and oldest method for CFD, but it has limitations in terms of accuracy, stability, and mesh quality.

4 CFD Challenges

CFD is a powerful and useful tool for automotive design, but there are some challenges and limitations that should be taken into consideration. Turbulence modeling is essential for CFD, however it introduces errors and uncertainties depending on the choice and calibration of the model. Mesh generation is another key step in CFD, as it affects accuracy, convergence, and computational cost. This process can be difficult for complex and curved geometries, like cars, requiring careful selection of mesh type, size, quality, and refinement. Validation and verification are also necessary for CFD to ensure reliable and realistic results. This involves comparing the CFD results to experimental or analytical data to assess accuracy, as well as assessing numerical errors and uncertainties from discretization, solution, and post-processing of the problem. Both validation and verification can be difficult and time-consuming for complex and transient flows.

5 CFD Tips

To get the most out of CFD for automotive design, there are some tips and best practices to follow. Firstly, you should have a clear idea of your objectives and requirements before starting the simulation. This will help you choose the right CFD tool, method, model, and settings for your problem. Secondly, it’s important to simplify your geometry and boundary conditions as much as possible without compromising accuracy and relevance of your results. Lastly, a sensitivity analysis can be used to evaluate how your CFD results depend on various parameters and to identify optimal values. It can also help validate and verify your CFD results by comparing them with different data sets or cases.