This study investigates the dynamics and runout of particle-water mixture column collapse using a modelling method coupling Discrete Element Method (DEM) and Volume of Fluid (VOF). From the numerical results, we observe similar and distinct responses between the dry and saturated mixture flows. Both exhibit two different flow behaviours for low and high column collapse. However, the presence of water reduces dissipative interactions between particles, hence increasing the mobility of mixture flows compared to their dry counterparts. The reduction of particle interaction forces also weakens the transition from sliding-dominant to inertial-dominant flows with increasing column aspect ratio. Therefore, the runout distance of mixture flows can be described by a single scaling law rather than by two different functions as for the dry flows. Additionally, the impacts of particle density on mixture flows become more significant in which the flows run out less and retain greater height with increasing particle density.
