Dynamic Tailgate Water Management Simulation Using Smoothed Particle Hydrodynamics

Opening a tailgate can cause rain that has settled on its surfaces to run off onto the customer or into the rear loadspace, causing annoyance. Relatively small adjustments to tailgate seals and encapsulation can effectively mitigate these effects. However, these failure modes tend to be discovered relatively late in the design process as they, to date, need a representative physical system to test – including ensuring that any materials used on the surface flow paths elicit the same liquid flow behaviours (i.e. contact angles and velocity) as would be seen on the production vehicle surfaces. In this work we describe the development and validation of an early-stage simulation approach using a Smoothed Particle Hydrodynamics code (PreonLab). This includes its calibration against fundamental experiments to provide models for the flow of water over automotive surfaces and their subsequent application to a tailgate system simulation which includes fully detailed surrounding vehicle geometry. This approach simulates the accumulation of rain on the rear surfaces of a stationary vehicle over the course of 60 s, which is followed by a drainage period of 20 s (rain source off). Once the starting conditions have been set, the simulation captures the dynamics of the tailgate opening and subsequent surface water run-off. This enables the mechanisms of run-off into the rear loadspace to be explored. Further, we also show the effect of a small modification to the tailgate encapsulation, demonstrating, by reference to physical test, that this simulation method can accurately replicate both the failure mode and its mitigation.