(115c) Collisional Dissipation Rate of Flexible Rods Measured Using Driven and Non-Driven DEM Simulations

Authors: 
Buettner, K. E., University of Florida
Guo, Y., Zhejiang University
Curtis, J. S., UC Davis
Bello, L., University of Florida
Particle flexibility is a complex phenomenon that has a significant effect on common particle systems (e.g. biomass refining). Current large-scale simulation techniques are far from being able to describe flexible particles, but discrete particle method (DEM) simulations offer the opportunity to investigate important particle-particle interactions. These interactions include the collisional dissipation rate, which describes the decrease in energy over time due to particle-particle collisions.

Homogeneous cooling system (HCS) and shear-flow (SF) simulations are used to investigate the effect of particle flexibility on the dissipation rate. As particles transition from rigid to flexible, new vibrational and potential energy degrees of freedom are introduced and accounted for in the energy loss due to collisions. As a particle becomes more flexible (decrease in Young’s modulus) the collision frequency decreases due to increased contact time. Thus, in systems where no energy is lost due to flexibility, the collisional dissipation rate decreases. The bond damping coefficient, describes energy loss due to flexibility, is found to be a more significant contribution to the collisional dissipation rate compared to the Young’s modulus and coefficient of restitution. As the bond damping coefficient increases, the collisional dissipation rate increases until it reaches a plateau. The effect of the coefficient of restitution and bond damping coefficient on the dissipation rate can be isolated and summed to create a model that is applicable for two-fluid simulations.