University of Natural Resources and Life Sciences, Vienna (BOKU) - Research portal
Gewählte Doctoral Thesis:
Miguel Angel Cabrera
(2016):
Experimental modelling of granular flows in rotating frames.
Doctoral Thesis - Institut für Geotechnik (IGT),
BOKU-Universität für Bodenkultur,
pp 212.
UB BOKU
obvsg
FullText
- Abstract:
- Geophysical flows are often related to natural hazards involving a combined action of granular debris immersed in a fluid (e.g. debris flows, hyperconcentrated flows, and mudflows). The magnitude and developed inertia in a geophysical flow makes them one of the most common and dangerous phenomena in mountainous regions. Based on historical data, empirical relations, field observations, and simplified numerical simulations, engineers and public officers face the challenging task of mapping hazard zones, planning prevention methods, and designing protection structures. Being this the current situation, a better understanding of the physics of geophysical flows may lead to improvements in prevention systems. This study addresses the interactions between particle and fluid phases with laboratory model tests, sharing many similarities with field geophysical flows while controlling the stress state and mixture components in a laboratory scale. The flow dynamics of a particle-fluid mixture, specifically the formation of a granular-front, are studied in a large rotating drum. Furthermore, the behaviour of granular flows down an inclined plane is studied in a geotechnical centrifuge. In this configuration, the scaling of the driving acceleration in a dry granular flow is studied and extended to the simulation of viscous granular suspensions. The experimental results provide a database for the development and validation of numerical models, with known boundary conditions and material composition. Excellent agreement is found in the analytical and numerical validation of the granular-front mechanisms, and the simulation of rapid granular flows in an augmented acceleration field. This work highlights the importance of simplifying complex processes into reasonable time and length scales able to account and describe the interactions of geophysical flow.
- Betreuer: Wu Wei
- 1. Berater: Kaitna Roland