Eulerian-Lagrangian Modeling of contamination on exterior of a NEVS Vehicle

Abstract

The rear view mirror design plays an important role for the resulting cleanliness of the driver’s side-window when cruising in rainy conditions. The visible field and the mirror glass must be as clean as possible. The flow around a rear-view mirror is inherently unsteady and vortex dominated. The contaminant particles (rain droplets) hit the mirror body and moves as wall film to a separation point that is governed by the mirror design. When the droplets separate, they can either enter the mirror wake or follow the ambient flow to leave the car. In this thesis, the complete process was modeled. It is shown how mirror design can be used to minimize the contamination areas to have maximum visibility. First, a benchmark study was done to understand the governing parameters of droplet and fluid film flow on a simplified geometry using the CFD software Star-CCM+. The flow was modeled using unsteady RANS and droplets were tracked using Lagrangian Particle Tracking (LPT). The conclusions from the benchmark study were implemented on the full vehicle model of NEVS vehicle. The simulation results were compared with a contamination test performed at NEVS climate tunnel.