(110d) A Kinetic Approach to Simulating Spherocylindrical Particles

The characteristics of granular flows exhibit varying behavior dependent on the shape of the individual particles. In the case of non-spherical particles, analytical closures for determining the characteristics of granular flows such as the equation of state is mostly unknown. Given the relative difficulty in physically measuring granular flows non-intrusively, we look to numerical methods to understand more complex granular flows. Unfortunately, deterministic discrete element methods are restricted to relatively small-scale systems to limit the number of contact forces that must be resolved to a computationally manageable size. To extend numerical solutions to large scale granular flows, particles can be treated as an ensemble, and the particle interactions can be resolved stochastically, akin to the direct simulation Monte Carlo (DSMC) method. Here, we extract various quantities needed to formulate a DSMC-like method for spherocylindrical particles. Pairwise collisions between spherocylinders are deterministically simulated using a soft-sphere discrete element method and consolidated into probability density and scattering functions. Collisional cross sections and their dependence on the initial conditions of the particle pair, e.g. orientation and rotational energy, are also measured from the discrete element simulations. Granular gases composed of spherocylinders are simulated to determine bulk characteristics such as the collision frequency and rotational relaxation time. The measured properties from discrete element simulations are then incorporated into a direct simulation Monte Carlo solver. The DSMC simulations results are compared to deterministic discrete element simulations and the accuracy and computational costs of the DSMC approach are discussed.