[H-DS07] Landslides and related phenomena

[HDS07-P10] The effects of irregular-shaped particles on the granular rheology of dense granular flow

*Li-Yen Su¹, Chi-Yao Hung¹ (1.National Chung Hsing University)

Keywords:granular rheology, irregular-shaped particle, Refractive Index Matching Material

External forces, such as gravity and streams, can drive granular flows as a moving layer and influence the surrounded landscape evolution. Adopting an appropriate rheology model is crucially important to understanding granular flow dynamics. However, in previous research, the rheology models were developed and tested in the regular shape of the particle. To understand the effect of the shape of the particles, we adopt irregular-shaped fused quartz sand for the experiments. Also, in this study, to avoid the boundary effect and get more insight from the interior flow, we use a blend of white mineral oils or aqueous glycerin (Refractive Index Matching material set) to achieve optical assessable granular flow. We performed the experiments with a tilted tube (30~50 degrees) and applied an adjustable upward flow by a well-controlled gear pump to conduct a stationary flow condition. We acquire the interior measurement of the granular motions by employing laser illumination, fluorescent dye, and a high-speed camera. To capture the movement of irregular-shaped particles, we develop a new method to determine the particle's position and apply the particle tracking velocimetry (PTV) method to build the flow's velocity field. We test the existing rheology models with the experimental results by varying the flow condition. In the end, we propose a modified model for the irregular-shaped particles.