Redefining Speed and Efficiency in Automotive CFD Workflows with Fidelity CFD

In today's advanced design processes, computational fluid dynamics (CFD) plays a vital role in improving and increasing the efficiency of products while reducing the need for extensive and costly physical testing. Over the last decade, the continuous improvement in tools and methods has significantly boosted productivity and reduced time to results. A key revolution in this space has been the advent of GPU-accelerated solvers that offer far greater performance per dollar compared to traditional CPUs. Despite these advancements in solver performance, one of the major challenges that engineers still face in CFD workflows is preprocessing (geometry entry and clean-up). Indeed, nearly 75% of CFD workflow efforts and time are spent at this stage.

Percentage of CFD workflow time & effort

In particular, automotive geometries tend to be intricate, often requiring “cleaning” before a final mesh can be achieved and CFD simulation begins. This process can take engineers days or even weeks as they iterate multiple times using geometry preparation and mesh generation tools. Cadence's Fidelity CFD software aims to address this bottleneck by enhancing traditional preprocessing workflows. With advanced automation and best practices, the software reduces preprocessing and meshing time from days to hours, generating high-fidelity meshes with 100% viscous layer coverage for highly accurate results.

Fast and Versatile Simulation Workflows

External aerodynamics solution showing streamlines colored by velocity (Image Courtesy: Toyota)

An optimal CFD workflow follows several essential principles:

• Fast: to allow CFD engineers to focus on optimizing design performance.

• Flexible: capable of seamlessly integrating into any existing workflow (termed "plug and play").

• Robust: ensuring clean and watertight operations.

• Lean: retaining only the parts and systems relevant to the simulation.

These core principles are at the heart of Cadence’s Fidelity CFD software products.

Seamless Integration and Customization

Automotive original equipment manufacturers (OEMs) often use diverse CAD formats and customized product lifecycle management (PLM) tree structures, making robust and flexible preprocessing capabilities essential. Surface and mesh generation steps often vary by customer and application but share common operations. The Cadence Fidelity workflow supports executing these necessary operations independently while seamlessly integrating with existing workflows. Cadence collaborates with OEMs worldwide, enhancing CAD-to-CFD performance through workflow automation and algorithms incorporated through a Python API.

Comprehensive Model Preparation

From CAD to watertight geometry in less than an hour (Image Courtesy: Honda)

For detailed predictions of external aerodynamics, air conditioning, or thermal management, model preparation with multiple CAD components or assemblies is essential. The challenges involve identifying all relevant surfaces “visible” to the flow and creating a watertight model needed for volume mesh generation. Fidelity automates this sealing process using the AutoSeal feature, which detects and seals the geometry gaps and holes, preserving the original geometry. With AutoSeal, the entire process of closing cabin space holes, which traditionally takes an experienced engineer about a week, is condensed to just an hour.

Efficient Meshing Options

Fidelity CFD software further provides various meshing options tailored for the automotive industry, such as full hexahedral meshes with hanging nodes and also mixed element conformal meshes. The automated volume mesh generation functionalities include:

• Fast and robust algorithms for reliable mesh generation for large, complex geometries.

• 100% viscous layer coverage to enhance boundary layer resolution.

• Mesh optimization algorithms to meet specific CFD solver quality criteria, ensuring optimal results for all classes of flow solvers.

• High-quality meshes for more robust computations, improved solver convergence, and shortened runtimes.

Hopium Machina CAD model (top) and close-up of the surface mesh (bottom) (Image Courtesy: Hopium)

Fidelity's meshing tools accommodate a wide range of simulation cases. The software enables automated meshing with minimal user intervention and offers manual grid control capabilities for detailed surface and volume mesh customization.

Export and Automation through Python API

Fidelity’s Python API provides users with automation capabilities for the entire CAD cleanup, repair, and meshing workflow, supporting headless operations. The platform also includes mesh optimization and export features for all major commercial and open-source-based CFD solver formats.

Automotive CFD Workflow Impact

Fidelity's CFD software enhances preprocessing and meshing workflows in the automotive industry, leading to increased efficiency in OEM workflows. These improvements are quantified by comparing turnaround time (TAT) from raw CAD import to volume mesh generation and assessing the performance enhancements achieved by Fidelity constructs in real-world applications, like those demonstrated by Toyota Motor Europe.

Impact of Fidelity Autoseal and Hexpress on Toyota Motor Europe’s CFD pre-processing workflow. Extracted from Cadence TechTalk February 16th, 2022 (Image Courtesy: Toyota Motor Europe)

Conclusion

Reducing preprocessing and meshing time from weeks to hours, generating high-quality meshes with complete viscous layer coverage, and enhancing any stage of pre-processing or meshing workflows are just a few of the robust automation capabilities offered by Cadence’s Fidelity CFD tools.

Watch the webinar Toyota Drastically Reduces Simulation Time with Automatic CFD Pre-Processing Workflow to learn how Fidelity CFD Accelerates Automotive CFD Workflow