ESR9 Alessandro Leonardi

Research project description

Hybrid Avalanches - Debris flow simulations with Discrete Elements and Lattice-Boltzmann

Fellow:                              Alessandro Leonardi

Supervisor:                      Prof. Hans J. Herrmann

Institution:                        ETH Zurich, Institute for Building Materials

Debris flows are fast mass movements of mixed debris and water that are common in mountainous terrains. They originate after heavy rainfall and can be imagined as liquefied landslides. They have been subject of interest from the community for their large destructive effects, with damage to properties and thousands of related casualties every year. Their heterogeneous composition, with a viscoplastic fluid and the presence of a relevant granular solid phase, make them a challenging problem for physical and numerical description of the phenomena.

This project aims to develop a model for the simulation of debris flows, fully coupling the two phases. A Discrete Element approach is used for the description of the solid phase, with a realistic particle size distribution, while the fluid phase is solved with a Lattice-Boltzmann Method with a non-Newtonian rheology and the presence of a free surface.

The numerical results provide insight into complex segregation, transportation and sedimentation phenomena, essential for understanding and predicting the run-out mechanism of debris avalanches and their interaction with obstacles and retaining structures.

The model is being validated through a comparison with the rotating drum experiments of Miguel Angel Cabrera. Future collaborations include the comparison with the CFD mixture theory simulations of Xiannan Meng and the development of a hybrid FEM-LBM model with Lorenzo Benedetti.

 

Figure 1: Hybrid avalanche flowing over an incline. Colors are used to represent the state of the fluid in the middle cross section (red=unyielded, blue=yielded) and arrows to show particle speed.