Transient, 3D CFD, Moving Mesh Simulation of Vehicle Water Wading in a Water Tunnel with Inclined Entry-Exit

Water wading tests are commonly performed for vehicles to ensure the functional integrity of different under-hood components at different water depths. This test has its relevance in both conventional Internal Combustion (IC) engine-based vehicles and Electric Vehicles (EVs). In IC engines, it is important for designing the Air Induction System (AIS), and for EVs, it helps to check the wetting of critical electrical and electronic components. The experimental setup for this test includes a long water tunnel where the car enters and exits the pool of water through a ramp. This work is an extension of the work done by Varshney et al. [6] where the Moving Reference Frame (MRF) technique was used to account for the motion of the car and the rotation of the wheels. The current work uses mesh morphing techniques to account for the motion of the vehicle and the rotation of the wheels that replicates the actual test conditions, including the inclination of the vehicle on the ramp. The entire pre-processing, post-processing, and the 3D CFD simulation have been done using commercial code, Simerics MP+®. Explicit VOF multiphase approach has been followed to predict the air-water interface. The simulation necessitates considering a big computational domain along with the actual geometry of all the under-hood components that make the simulation computationally expensive. Hence, optimization of computational time while ensuring minimal numerical diffusion are vital contributions from the work. Wading analysis has first been done on a DrivAer model [8] and later, a detailed production car model is simulated. Quantification of the level of water in the underhood compartment has been done at different water heights. Results of the wave pattern formed around the car and other under-hood components are also analysed.