# Dynamic Simulation of Hillslope Landslide with openFoam - Tutorial

Landslides are movements of rock, mud, or debris caused by rains, earthquakes among other factors. Landslides are harmful to people, houses, highways and general infrastructure. Based on geotechnical surveys, the zones with high vulnerability to landslides can be assessed as well as conditions that increase the risk of landslides; however there isn´t much done in assessing the dynamic behavior of the landslide.

This tutorial shows the whole procedure to simulate a landslide of a hillslope from a initial condition of failure. The tutorial was done with the interFoam solver from openFoam on a non- Newtonian flow. The fluid has a variable kinematic viscosity (nu) based on the Bird-Carreau model. Failure scenario last only 6 seconds and results were recorded every 0.1 seconds. Final geometry and the landslide development were analyzed with paraView with predefined views (paraView states).

## The non Newtonian behavior of landslides

Hillslopes lanslides have a non Newtonian behavior becuase it viscosity (deformation resistance) is not constant and depends on the strain rate (deformation rate). On low strain rates, the material is more viscous and flows less, on high strain rates, the material turns less viscous and flows more. To represent this fluid behavior there is a need of computational fluid dynamics (CFD) software as OpenFOAM with appropriate rheological models.

OpenFOAM is a powerful open source CFD software that has 7 options to represent non Newtonian fluids, all of which correlate the kinematic viscosity (nu) to the deformation rate and they are implemented on the transportProperties folder of the model file system.

From our research, the rheological models that are more suitable to represent landslides are Bird-Carreau and Herschel-Bulkley since they flow better at high velocity and stop gradually at low velocity. In order to understand a flow behavior of a landslide please have a look to this video.

## Input data

For the simulation of a hillslope landslide the following data is required:

• Slope topography
• Fault zone geometry
• Soil density

It is advisable to have a survey or fotographic register from similar lanslides on the area in order to calibrate the Bird Carreau coefficients.

## Modeling applications

Results from this simulation can be applied in:

• Emergence response plans
• Feasibility of countermeasures
• Geotechnical vulnerability studies

## Landslide animation

This is a animation of a landslide from the central part of a slope

## Tutorial

### First part

This part explains the model file system and the files that setup the initial conditions, the model geometry, the Bird Carreau parameters for the non Newtonian fluid as well as other model files.

### Second part

With the complete simulation, results are shown in paraView with predefined views stored in a "stage".