A Fast and Fully Automated Cartesian Meshing Solution for Dirty CAD Geometries

The most time-consuming step in an external aerodynamics or underhood CFD process is that of generating a usable mesh from CAD data. Conventional mesh generators require a water-tight surface mesh before they can generate the volume mesh. Typical CAD surface data available for mesh generation is far from satisfactory for volume mesh creation: no node-to-node matching between mating parts, minute gaps, overlapping surfaces, overlapping parts, etc. To clean up this kind of data to a level that can be used for volume mesh creation requires a lot of manual work that could take a couple of weeks or more to accomplish. This paper presents a fast and fully automated, Cartesian cell dominated projected mesh generation algorithm used in CFD-VisCART that eliminates the need for CAD data cleaning, thus shaving off weeks worth of time off the design cycle. This process of mesh generation involves the volume mesh cells being generated first and then projected onto the surfaces of the CAD model to create the surface mesh automatically. Additionally, this projection method has intrinsic advantages when dealing with minute gaps and overlapping parts. Shrink-wrapping (to cover up larger holes or simplify an assembly of parts), automatic hole detection (to detect any mesh leaks), gap handling (to ensure proper mesh resolution between neighboring parts) and such other tools together with the novel features of the projection algorithm mentioned above can reduce turnaround time for mesh generation from 3–4 weeks to less than one day.