Special to DVN by Mentor Graphics
One needn’t be involved professionally in automotive lighting to see how much the design of the lights has changed and become much more complex. But a look at the outside of the car doesn’t show all the new technology, hidden behind the bezels and lenses, for adaptive beams, LED matrices, etc. Each and every LED might have its own lens, while light guides with textures and structures are increasingly used to direct the light as needed. All these new structural changes and components mean today’s lamps are vastly more complex than yesterdays. And that’s without even mentioning cars with multiple choices of headlight systems—full LED, matrix LED, or HID, in the case of the Audi TT, for example—which increase the variety of systems even more. Constant across all the variants is the need for thermal management to assure the performance and reliability of the lighting system. This task has to be handled with CFD (Computational Fluid Dynamics), as making prototypes for each change to each variant would be inefficient and costly.
In general CFD tools require a mesh in order to discretise the geometry in small elements which will then be calculated by the solver. Such a mesh generation in the new lighting systems becomes very time consuming and often even before the mesh in generated a CAD model preparation is required to simplify the geometry for the mesh generation. When taking a closer look at the actual geometry of a headlight, one can see a lot of fine details such as the sawtooth structure of the light guides or small ribs on the reflector or bezels for directing low beam light upward onto overhead road signs, or the small facetted surfaces of the orange plastic of the turn signal. Such small structures are difficult to model in every traditional meshing process. But the worst part of it is when the mesh is finally completed after several hours or days of manual work and then the design has changed slightly and the first simulation hasn’t even run. With the automotive lighting industry being so strongly linked to design, a better solution is required that is much more upfront in the design process and automates laborious task such as meshing and eliminates the geometry simplification.
Such a frontloading approach to automatically create a highly accurate mesh directly on the native CAD geometry is the approach pursued by Mentor Graphics’ FloEFD and its integration in Catia V5, ProE/Creo and Siemens NX. This enables engineers to always be up-to-date with the simulation on the latest design and automatic meshing reduces the manual workload for the user who can rather take care of other things in his schedule.