What friction models are used in RAMMS?Answer: RAMMS (Avalanche and Debrisflow modules) employs a Voellmy-fluid friction model. This model divides the frictional resistance into two parts: This model has found wide application in the simulation of mass movements, especially snow avalanches. The Voellmy model has been in use in Switzerland for a long time and a set of calibrated parameters is available. The frictional resistance S (Pa) is depicted above, where ρ is the flow density, g gravitational acceleration, φ the slope angle, H the flow height and U the flow velocity. The Voellmy equation has been modified to include cohesion. |