Assessment of Passenger Car for Surface Dirt Contamination in Wind Tunnel

Self-soiling or surface contamination is usual phenomenon observed during rainy season wherein dirt on road are picked by rotating wheel and later released in air as fine particles. These released dirt particles are further carried by airflow around vehicle and as a result stick on vehicle exterior surfaces leading to surface contamination. Surface dirt contamination is one of critical issues that need consideration during early phase of vehicle development as vehicle styling plays a critical role for airflow around vehicle and therefore settling of dirt on vehicle exterior surfaces. Non consideration of such aspects in design can lead to safety issues with likely non-functioning of parking sensors, camera and visibility issues through ORVM, tailgate glass etc. Hence it is important to understand physical as well as digital techniques for assessment of vehicle for surface dirt contamination.

This paper looks at means for accessing the surface contamination through physical test which can be repeatable, reliable and boundary conditions that are well understood and controlled so that they can be used as reference for digital simulations as well. This paper talks about outcome of self-contamination physical test in a wind tunnel and its validation with digital test using commercial CFD code with reference to case study on a SUV.