Passenger Car Water Wading Evaluation Using CFD Simulation

Water Wading refers to the situation where a car is moving through relatively deep water at low speed. The challenges of an automotive Original Equipment Manufacturer (OEM) is to integrate the functional parts like bumper, bumper grille, engine undercover, intake system etc., to enhance the vehicle quality and performance. One of the challenges in vehicle front end and engine room design is to prevent water entry into the air intake system during wading. If significant amount of water enter the air intake, some of the water could subsequently enter the engine cylinder, which would damage the critical components within the engine beyond repair.

In general practice wading tests have been carried out during proto stage of vehicle development program to ensure vehicle performance. However a Computational Fluid Dynamics (CFD) method for carrying out water wading calculations early during the development phase offers reduction in development cost and time for a new vehicle. This paper explains the CFD methodology to evaluate the water entry into the air intake system. A detailed process development has been done for simulation methodology to finalize best meshing parameters and analysis procedure based on correlation with physical testing. The CFD and physical testing results are in ±10% of deviation. Various design modifications like changes in intake snorkel position and its design are attempted to improve the overall performance.