Numerical Investigation of Wiper Drawback 2019-01-0640
Windscreen wipers are an integral component of the windscreen cleaning systems of most vehicles, trains, cars, trucks, boats and some planes. Wipers are used to clear rain, snow, and dirt from the windscreen pushing the water from the wiped surface. Under certain conditions however, water which has been pushed from the windscreen by the wiper can be pulled back on the windscreen by aerodynamic forces introduced by the wiper motion, wiper pull back. This is an undesirable phenomenon as the water which is pulled back on to the windscreen can reduce driver visibility and makes the wiper less effective.
The phenomena of wiper pull back can be tested for in climatic tunnels using sprayer systems to wet the windscreen. However, these tests require a prototype vehicle, which means that the tests are done fairly late in the development of the vehicle. Furthermore, these results do not provide significant insight into the mechanisms driving the wiper pull back.
In order to better understand wiper pull back a numerical simulation of a configuration known to exhibit wiper pull back is simulated. This requires the inclusion of moving wipers, a surface film model, and an aerodynamics solver.
Using the results of this simulation, the forces causing the pull back of the water film, along with the mechanism for introducing these forces are studied. Through understanding the driving factors in wiper pull back, it can be avoided earlier in the development cycle.
Jonathan Jilesen, Adrian Gaylard, Tom Linden
Dassault Systemes, Jaguar Land Rover, Exa Corporation