Numerical simulation of 2D granular flow entrainment using DEM
- 315 Downloads
To understand the entrainment process in granular flow, numerical experiments have been conducted using a Discrete Element Method model. A flow channel of 8 m long with \(15^\circ \) slope is setup with monitoring points located in an erodible bed. Particles, ranging from 3 to 4 mm in diameters, are used in the simulations. In the simulations, translational, rotational and average velocities, total volume, shear stresses are calculated in the measurement circles. The sizes of the measurement circles have been varied to see their effects on the results. It is found the minimum size of the measurement circles should include 20–30 particles. An new analytical model has been developed to calculate entrainment in granular flow. Results of the numerical experiment are compared with analytical model. Shear stresses at the interface between flowing particles in motion and the immobile particles in the channel bed, change of depth of erosion and entrainment rate are used to verify the analytical model. It is found that the calculated shear stresses in the PFC model agree well with the shear stresses calculated using Mohr–Coulomb frictional relationship in the analytical model. The calculated depth of erosion using the new analytical model is also compared with that from dynamic and static entrainment model. The results indicates that the analytical model is able to capture the mechanism of erosion and it can be used in granular flow analysis.
KeywordsGranular flow Entrainment Numerical experiment Debris flow Discrete element method
This study is sponsored by the Natural Science and Engineering of Canada Discovery Grant.
Compliance with ethical standards
Conflict of interest
We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled.
- 3.Berger, C., McArdell, B.W., Schlunegger, F.: Direct measurement of channel erosion by debris flows, Illgraben, Switzerland. J. Geophys. Res. Earth Surf. 116(F01002) (2011). https://doi.org/10.1029/2010JF001722
- 6.Caquot, A.: Equilibre des Massifs a’ Frottement Interne. Stabilite des Terres Pulv6rents et Coherentes. Gauthier Villars, Paris (1934)Google Scholar
- 8.Chigira, M.: Dry debris flow of pyroclastic fall deposits triggered by the 1978 Izu-Oshima-Kinkai earthquake: the “collapsing” landslide at Nanamawari, Mitaka-Iriya, southern Izu Peninsula. Nat. Disaster Sci. 4(2), 1–32 (1982)Google Scholar
- 11.Cundall, P.A.: A computer model for simulating progressive, large scale movements in blocky rock systems. In: Proceedings of the International Symposium on Rock Mechanics, Editors: Anonymous, Nancy, France, October 4–6, 1971, vol. 2, pp. 129–136. Rubrecht, Germany (1971)Google Scholar
- 20.Itasca, Consulting Group Inc., PFC2D Particle Flow Code in 2 Dimensions. User’s Guide (2002)Google Scholar
- 21.Iverson, R.M., Logan, M., LaHusen, R.G., Berti, M.: The perfect debris flow? Aggregated results from 28 large-scale experiments. J. Geophys. Res. Earth Surf. 115(F03005), (2010). https://doi.org/10.1029/2009JF001514
- 23.Iverson, R.M.: Elementary theory of bed-sediment entrainment by debris flows and avalanches. J. Geophys. Res. 117(F03006) (2012). https://doi.org/10.1029/2011JF002189
- 31.Mangeney, A., Roche, O., Hungr, O., Mangold, N., Faccanoni, G., Lucas, A.: Erosion and mobility in granular collapse over sloping beds. J. Geophys. Res. 115(F03040) (2010). https://doi.org/10.1029/2009JF001462
- 33.McCoy, S.W., Kean, J.W., Coe, J.A., Tucker, G.E., Staley, D.M., Wasklewicz, T.A.: Sediment entrainment by debris flows: in situ measurements from the headwaters of a steep catchment. J. Geophys. Res. Earth Surf. 117(F03016) (2012). https://doi.org/10.1029/2011JF002278
- 37.Melosh, H.J.: Acoustic fluidization: can sound waves explain why dry rock debris appears to flow like a fluid in some energetic geologic events? Am. Sci. 71(2), 158–165 (1983)Google Scholar
- 41.Reid, M.E., Iverson, R.M., Logan, M.A.T.T.H.E.W., LaHusen, R.G., Godt, J.W., Griswold, J.P.: Entrainment of bed sediment by debris flows:results from large-scale experiments. In: Genevois R., Hamilton, D.L., Prestininzi, A. (eds.) Proceedings of Fifth International Conference on Debris-flow Hazards Mitigation, Mechanics, Prediction and Assessment, Casa Editrice Universita La Sapienza, Rome, June 14–17, 2011, pp. 367–374 (2011)Google Scholar
- 43.Remaître, A., Malet, J.P, Maquaire, O.: Sediment budget and morphology of the 2003 Faucon debris flow (South French Alps): scouring and channel-shaping processes. In: Malet J.P., Remaitre A., and Bogaard T. (eds.) Proceedings of the International Conference on Landslide Processes: From géomorphologie Mapping to Dynamic Modelling, Strasbourg, France, February 6–7, 2009, pp. 75–80. CERG, Strasbourg (2009)Google Scholar