Coupled Multibody Dynamics and Smoothed Particle Hydrodynamics for Modeling Vehicle Water Fording

Multibody dynamics and smoothed particle hydrodynamics (SPH) are integrated into one solver for predicting the water fording dynamic response of ground vehicles. Multibody dynamics models are used for the various vehicle systems including: suspension system, wheels, steering system, axles, differential, and engine. A penalty technique is used to impose joint and normal contact constraints (between the tires and ground, and between the tires/vehicle body and the fluid particles). An asperity-based friction model is used to model joint and contact friction. Water is modeled using an SPH particle-based approach along with a large eddy-viscosity turbulence model. A contact search algorithm that uses a Cartesian Eulerian grid around the water pool is used to allow fast contact detection between particles. A recursive bounding box contact search algorithm is used to allow fast contact detection between polygonal contact surfaces (representing the tires and vehicle body) and the fluid particles. The governing equations of motion for the solid bodies and the fluid particles are solved along with joint/constraint equations using a time-accurate explicit solution procedure. The integrated solver is used to predict the dynamic response of a Humvee-type vehicle moving through a shallow water pool.