Water Ingress Analysis and Splash Protection Evaluation for Vehicle Wading using Non-Classical CFD Simulation 2017-01-1327

Physical testing of a vehicle wading through water is performed to gauge its capability to traverse through shallow to deep levels of water, wherein various vehicle performance parameters are observed, recorded and analysed. Jaguar Land Rover (JLR) has instigated and established a comprehensive CAE test procedure for assessing the same, which makes use of overset mesh (in a CFD environment) for a non-traditional approach to vehicle motion. The paper presents investigations made into the established wading physics, in order to optimise the splashing and water jet modelling. Large Scale Interface model was implemented instead of the previously standardised VOF-VOF fluid phase interaction model, and a comparison is made between the two. The implemented wheel rotation approach was scrutinised as well and appropriate inferences are drawn. JLR has devised an extended simulation methodology, making use of the passive scalar model, to understand water impingement and splashing in a greater detail; which are the two critical performance parameters during vehicle wading. Passive scalar acts as a pseudo catalyst in the target fluid phase of the multiphase CFD simulation. Analysis carried out using this model gives the amount of water ingress from specific locations on the vehicle and also the amount of water subsequently splashing on the pre-set target locations or components in the engine bay. The assessment was performed on a simplified block model, scaled down with reference to vehicle dimensions, which permitted reiterative simulation setup with minimum computational cost. The methodology was successfully implemented on a full scale JLR vehicle later. Thorough physical testing of vehicles was carried out so as to understand and assess water ingress and in turn, drive further developments in CAE.