Computational Fluid Dynamics Blogs

Introduction

Healing geometry, setting the domain, grid discretization, solution initialization, and result visualization, are steps in a CFD workflow. Preprocessing, if done efficiently, is the first step to an accurate CFD solution that can save both human hours and labor. The geometry cleanup tools available in the market to repair surfaces and create watertight geometries (significant in CFD analysis for heat and mass transfer between surfaces or volumes of a body) often fail in automated workflows. Significant advances have been made in numerical algorithms, turbulence modeling, and parallel computing for accurate CFD solutions; however, geometry clean-up continues to be a bottleneck in addressing complex geometries.

Figure 1. Watertight surface generation of a complete Toyota vehicle was reduced from 160 hours to 6 hours with Fidelity Autoseal

For detailed information on how this was done, watch Antoine Delacroix, Manager, Vehicle Performance Engineering R&D at Toyota Motor Europe, explain in an on-demand webinar:

(On-demand, register only once to get access to all Cadence on-demand webinars)

Today, automotive and aerospace industries have a shorter time-to-market, demanding faster design solutions. Therefore, CFD solutions that take months or weeks just for pre-processing are not feasible options in the competitive present. Cadence^® Fidelity CFD offers AutoSeal technology, a geometry clean-up tool for faster results for multiple design tests, reducing the time to meshing towards an efficient design process.

Challenges of Poor-Quality CAD Geometries

CAD geometries with extrusions, holes, and gaps can give a hard time and sometimes require several iterations before generating a definitive and high-quality mesh. Poor quality CADs and highly complex geometries lead to long preparation and set-up times and require manual input for a good quality mesh. It can be a laborious process, especially when it is necessary to test multiple design cases for an accurate product solution. In such cases, the complete automation of this preprocessing step would be beneficial.

User Benefits of Fidelity CFD AutoSeal

Fidelity CFD’s pre-processing solution works for a broad range of CAD formats without losing the prominent details of the geometry and meets the necessary user specifications. Geometry cleanup can save simulation time and is a crucial step in CFD analysis, often taking days or even weeks, depending on the complexity of the geometry. With Fidelity CFD, capping holes and cavities takes a few minutes or hours, saving both time and resources.

Figure 2. Fidelity AutoSeal closes 282 open surfaces or holes in a Titanic CAD model within 50 seconds using an 8-core computer.

Fidelity CFD AutoSeal technology automates the geometry clean-up process and enables quality meshing ready for CFD analysis in real-time. Based on successive octree refinements, AutoSeal can detect cells of a dirty geometry (both inside and outside the geometry), allowing the system to progressively identify missing surfaces under a user-defined threshold and automatically closing those open surfaces towards a cleaner geometry fit for accurate meshing.

Figure 3. AutoSeal user interface to configure three settings for an automated solution.

The Autoseal algorithm requires at least one inside and one outside point to determine the areas to close. To study the flow inside a car, you can define as many points as required. The user has total control.

And there is more! You can utilize Python scripts to automate the entire process of CAD preparation. It can be launched locally on workstations and even on distributed parallel using high-performance computing (HPC) clusters.

Conclusion

Fidelity CFD AutoSeal is a next-generation geometry clean-up solution that promises a breakthrough in faster meshing and simulation speed. While cleaning dirty CAD geometries or filling holes or gaps takes a big chunk of CFD solution time, AutoSeal can bring this down to a few minutes or hours.