Fig 1.
Velocity data of avalanche #20173032.
(a) Velocity (colorized) and flow depth vs. time. Note that, a flow detachment from the pylon occurred between 55 and 65 sec above 2 meters, resulting in the decreased local quality of the measurements, as shown by the scattered data, below the dashed red line. (b) Velocity profile extracted at the avalanche front (51.8 < t < 52.3). (c) Velocity profile extracted at the avalanche tail (78.7 < t < 79.2). On the three panels the dashed red lines indicates the height of the dense flow. The average air temperature during the event was -2°C.
Fig 2.
(a) Schematic of two particles i and j being in contact and bonded. (b) Parallel-bond contact model. The values/ranges of denoted values are found in Table 1. (c) Failure envelope of the bond. (d) Bond normal force as a function of normal interpenetration. (e) Bond shear force as a function of tangential interpenetration. (f) Bond bending moment as a function of bending rotation.
Table 1.
Parameters used in the simulations.
Fig 3.
Setup used for the simulations.
The dotted lines mark the periodic boundaries of the domain. Grey particles are simply a replica from the domain’s particle and are only shown for illustration. The velocity of particles (colorized) and the bonds between particles (black segments) are shown as an example.
Fig 4.
Velocity profiles for different combinations of aggregation number ηa and fragmentation number ηf.
For these simulations, Vini = 1 m/s and μg = 0.5.
Table 2.
Parameters and observations on the simulated flow regime scenarios.
Fig 5.
Velocity profiles (a,d,g), pressure profiles (b,e,h) and particles visualisations (c,f,i) for scenarios 1 (first row, ηf = 10, ηa = 0.1), 2 (second row, ηf = ηa = 10) and 3 (third row, ηf = 0.9, ηa = 2.2). Red and blue lines show σb and σa, respectively, for each scenario. Note that both lines are superposed in panel (e). The error bars display the standard deviation calculated from the averaging over t and .
Fig 6.
Velocity profiles (a,d,g), pressure profiles (b,e,h) and particles visualisations (c,f,i) for scenarios 4 (first row), 5 (second row) and 6 (third row). ηf = ηa = 0.1. Values of σb and σa are out of range in panels (b,e,h) but are indicated. The error bars display the standard deviation calculated from the averaging over t and .
Fig 7.
Effect of ground friction and initial velocity on plug flows.
(a) Mean velocity vs. ground friction after the time necessary for the flow to reach a steady state. (b) Mean velocity vs. time for Vini = 3, 5, 10 and 20 m/s and μg = 0.35. All simulations are run with ηf = 0.1 and ηa = 10.
Fig 8.
(a) Velocity profile, (b) particles vizualisation for scenario 7. ηf = 0.1, ηa = 10, μg = 0.35 and Vini = 10 m/s. The error bars display the standard deviation calculated from the averaging over t and .
Fig 9.
Comparison of experimental (red) and simulated (black) velocity profiles.
(a) Profile from Fig 1b compared with scenario 1. (b) Profile from Fig 1c compared with scenario 7.
Fig 10.
(a) Velocity (colorized) vs. height during a DEM simulation of transitional flow regime. (b) Maximum and average velocity of avalanche #20173032 vs. time in dark blue and blue, respectively. The figure also shows the maximum and average velocity of the DEM simulations vs. time in dark red and red, respectively. (c) Evolution of parameters ηf, ηa and μg vs. time in the simulation.