Investigating PDC Flow using DEM Simulations.

Pyroclastic Density Currents are hazardous, geophysical flows arising from volcanic activity that pose a significant risk to communities in close proximity to volcanoes. Their destructive nature is partly attributed to their incredible mobility, which allows them to reach exceptional distances. Due to their complexity, limited optical depth, unpredictable nature and dangerous conditions, the study of the dynamics of PDCs relies on a combination of field studies, experiments and numerical modelling. By implementing models that investigate the energy dissipation occurring at the particle scale, a better understanding of their mobility and runout can be achieved. This report uses a 2D Discrete Element Method approach with a non-cohesive contact model to simulate granular flow down a rough inclined plane with changing inclinations between 20-30 degrees to investigate real aspects of changing topography and its effect on runout distance. Higher inclinations had the greatest kinetic energy and during deposition, the uppermost layers of flow had the longest runout. The depositional phase during deceleration on horizontal slopes shows a backward accretion of particles, consistent with other findings. The results validated conceptual models derived from field studies at Mt Merapi and are in agreement with previous DEM models. The applicability of these results extends to rockfall avalanches that share a similar particle nature.