The video below shows the de-fogging process of the inner side of a head lamp used in common cars. Due to varying temperatures and air humidities in- and outside the unit, water may condensate on the inner surface of the lamp. For aesthetical and functional reasons it is necessary to either avoid the development of such a water film or reduce condensation quickly by means of efficient ventilation.
Computational Fluid Dynamics (CFD) can take on a major role in such a design and optimization process as turnaround times are usually faster and costs are lower compared to physical model testing. Thereby engineers quickly reach a state, which enables them to decide on the best geometry based on a large number of designs that had been simulated. De-fogging and de-icing are not only important in the case of the described problem, but also for the windscreen. By optimizing the air flow towards the windscreen inside the cabin, the sight of the driver may be improved and safety will be increased.