Massively Parallel Discrete Element Modeling of Wheeled Mobility on Granular Terrain

Quantitatively understanding wheeled mobility on granular terrain such as sand or gravel is critical for design and operations of ground vehicles for terrestrial or extra-terrestrial applications. While the Bekker-Wong theory of wheeled mobility and its derivatives have been used in many applications, the static nature of these formulations are limiting in understanding mobility in deformable terrain under dynamic mobility conditions. Single wheel hardware experiments in laboratory settings and detailed modeling of wheel-terrain interactions are two avenues currently being actively pursued to develop quantitative understanding of wheeled mobility. In this paper, we present findings of massively parallel discrete element modeling of wheeled mobility on granular media such as sand. We present a brief overview of the underlying methodology and then focus on the results of the simulation. In these simulations, we model the inter-granular interactions and interactions between the wheel and the granules with an objective of using high fidelity first-principles approach to capture emergent behavior in these complex and highly dynamic phenomena. These simulations typically model millions of granules and use highly scalable software and parallel computing resources to overcome the severe complexity of the problem. We present results of parametric studies with varying levels of both wheel penetration and mobility conditions. These have been modeled to present a quantitative perspective of the diverse behaviors encountered in wheeled mobility on granular terrain. We have retained the full complexity of the problem by simulating granules of the size encountered in real terrain to overcome the fidelity limited issues of other comparable methods that use much larger granules.