scholarly journals Verification of a 2D finite element debris flow model using Bingham and cross rheological formulations

2008 ◽  
Author(s):  
C. Martinez ◽  
F. Miralles-Wilhelm ◽  
R. Garcia-Martinez
Keyword(s):  
Finite Element ◽  
Debris Flow ◽  
Flow Model

scholarly journals A two-phase shallow debris flow model with energy balance

2015 ◽  
Vol 49 (1) ◽  
pp. 101-140 ◽  
Author(s):  
F. Bouchut ◽  
E.D. Fernández-Nieto ◽  
A. Mangeney ◽  
G. Narbona-Reina
Keyword(s):  
Energy Balance ◽  
Debris Flow ◽  
Flow Model ◽  
Two Phase

scholarly journals A system of conservative regridding for ice/atmosphere coupling in a GCM

2013 ◽  
Vol 6 (4) ◽  
pp. 6493-6568 ◽  
Author(s):  
R. Fischer ◽  
S. Nowicki ◽  
M. Kelley ◽  
G. A. Schmidt
Keyword(s):  
Finite Element ◽  
General Circulation ◽  
Flow Model ◽  
Source Code ◽  
Circulation Model ◽  
Surface Mass Balance ◽  
Ice Flow ◽  
Surface Mass ◽  
Flow Models ◽  
Ice Model

Abstract. The method of elevation classes has proven to be a useful way for a low-resolution general circulation model (GCM) to produce high-resolution downscaled surface mass balance fields, for use in one-way studies coupling GCMs and ice flow models. Past uses of elevation classes have been a cause of non-conservation of mass and energy, caused by inconsistency in regridding schemes chosen to regrid to the atmosphere vs. downscaling to the ice model. This causes problems for two-way coupling. A strategy that resolves this conservation issue has been designed and is presented here. The approach identifies three grids between which data must be regridded, and five transformations between those grids required by a typical coupled GCM–ice flow model. This paper shows how each of those transformations may be achieved in a consistent, conservative manner. These transformations are implemented in GLINT2, a library used to couple GCMs with ice models. Source code and documentation are available for download. Confounding real-world issues are discussed, including the use of projections for ice modeling, how to handle dynamically changing ice geometry, and modifications required for finite element ice models.

scholarly journals The use of the finite-element method for the simulation of ground water flow

1988 ◽  
Vol 7 (4) ◽  
pp. 174-183
Author(s):  
G. J. Van Tonder ◽  
J. F. Botha
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Ground Water ◽  
Water Flow ◽  
Flow Model ◽  
The Finite Element Method ◽  
Ground Water Flow ◽  
Available Information ◽  
Good Flow ◽  
Element Method

The present investigation is mostly concerned with the contribution that the finite-element method can make towards the simulation of ground water flow. After a brief introduction to the finite element method, it is applied to the Grootfontein dolomitic aquifer near Mafikeng/Mmabatho. This aquifer yields water for irrigation purposes as well as water for the township. By utilizing the available information a good flow model was constructed for this aquifer. The model is considered calibrated and verificated.

scholarly journals Back-calculation of the 2017 Piz Cengalo-Bondo landslide cascade with r.avaflow

2019 ◽  
Author(s):  
Martin Mergili ◽  
Michel Jaboyedoff ◽  
José Pullarello ◽  
Shiva P. Pudasaini
Keyword(s):  
Debris Flow ◽  
Flow Model ◽  
Rock Avalanche ◽  
Simulation Software ◽  
Process Models ◽  
Rock Fall ◽  
Model Parameters ◽  
Rock Slide ◽  
Glacier Ice ◽  
Initial Rock

Abstract. In the morning of 23 August 2017, around 3 million m3 of granitoid rock broke off from the east face of Piz Cengalo, SE Switzerland. The initial rock slide-rock fall entrained 0.6 million m3 of a glacier and continued as a rock(-ice) avalanche, before evolving into a channelized debris flow that reached the village of Bondo at a distance of 6.5 km after a couple of minutes. Subsequent debris flow surges followed in the next hours and days. The event resulted in eight fatalities along its path and severely damaged Bondo. The most likely candidates for the water causing the transformation of the rock avalanche into a long-runout debris flow are the entrained glacier ice and water originating from the debris beneath the rock avalanche. In the present work we try to reconstruct conceptually and numerically the cascade from the initial rock slide-rock fall to the first debris flow surge and thereby consider two scenarios in terms of qualitative conceptual process models: (i) entrainment of most of the glacier ice by the frontal part of the initial rock slide-rock fall and/or injection of water from the basal sediments due to sudden rise in pore pressure, leading to a frontal debris flow, with the rear part largely remaining dry and depositing mid-valley; and (ii) most of the entrained glacier ice remaining beneath/behind the frontal rock avalanche, and developing into an avalanching flow of ice and water, part of which overtops and partially entrains the rock avalanche deposit, resulting in a debris flow. Both scenarios can be numerically reproduced with the two-phase mass flow model implemented with the simulation software r.avaflow, based on plausible assumptions of the model parameters. However, these simulation results do not allow to conclude on which of the two scenarios is the more likely one. Future work will be directed towards the application of a three-phase flow model (rock, ice, fluid) including phase transitions, in order to better represent the melting of glacier ice, and a more appropriate consideration of deposition of debris flow material along the channel.

Finite-Element Model of Impact Loading and Deformation of a Flexible Steel Ring-Net Debris-Flow Barrier

2020 ◽  
Vol 21 (3) ◽  
pp. 04020026
Author(s):  
Aliena M. Debelak ◽  
Christopher A. Bareither ◽  
Hussam Mahmoud
Keyword(s):  
Finite Element ◽  
Debris Flow ◽  
Finite Element Model ◽  
Impact Loading ◽  
Element Model ◽  
Ring Net

scholarly journals Navier-Stokes Equation and Computational Scheme for Non-Newtonian Debris Flow

2014 ◽  
Vol 2014 ◽  
pp. 1-5
Author(s):  
Ignazio Licata ◽  
Elmo Benedetto
Keyword(s):  
Debris Flow ◽  
Flow Model ◽  
Computational Approach ◽  
Computational Scheme ◽  
Navier Stokes ◽  
Uniform Motion ◽  
Geological Data ◽  
Navier Stokes Equation ◽  
Grid Systems ◽  
Computing Effort

This paper proposes a computational approach to debris flow model. In recent years, the theoretical activity on the classical Herschel-Bulkley model (1926) has been very intense, but it was in the early 80s that the opportunity to explore the computational model has enabled considerable progress in identifying the subclasses of applicability of different sets of boundary conditions and their approximations. Here we investigate analytically the problem of the simulation of uniform motion for heterogeneous debris flow laterally confined taking into account mainly the geological data and methodological suggestions derived from simulation with cellular automata and grid systems, in order to propose a computational scheme able to operate a compromise between “global” predictive capacities and computing effort.

Assessing lahar hazards at Cotopaxi volcano (Ecuador) controlled by volcanic eruptions and glacier retreat

2020 ◽  
Author(s):  
Theresa Frimberger ◽  
Franziska Petry ◽  
Michael Krautblatter
Keyword(s):  
Debris Flow ◽  
Flow Model ◽  
Frictional Resistance ◽  
Volcanic Eruptions ◽  
Glacier Retreat ◽  
Permafrost Degradation ◽  
Turbulent Friction ◽  
Refraction Seismic ◽  
Cotopaxi Volcano ◽  
Input Parameters

<p>Lahars rank as one of the most destructive hazards at Cotopaxi volcano (5897 m asl) due to the presence of a massive glacier cap, the frequency of eruptions and the high population density in the surrounding, potentially inundated valleys. In 1877, Cotopaxi experienced the last major VEI 3-4 eruption, producing syneruptive lahars of 60-100 million m<sup>3 </sup>that travelled hundreds of km downstream.  Few lahar simulations based on empirical or fluid dynamic approaches exist for Cotopaxi, but here we introduce a calibrated numerical debris flow model capable of reproducing confluence and erosivity of flows.</p><p>In this study, we back-calculate the well documented 1877 lahar event using the 2D debris flow model RAMMS, which is based on the Voellmy-Salm friction approach and includes an entrainment algorithm. We first evaluate the sensitivity and range of possible model input parameters by systematically varying model inputs for release volume, density and frictional resistance (Coulomb type friction μ [-] and turbulent friction ξ [ms<sup>-2</sup>]). Supported by a probabilistic analysis, we find that a choice of historical and field-derived calibration metrics of the 1877 lahar event along the northern lahar trajectory can well constrain most likely input parameters for frictional resistance. Our results show that modelling large-scale primary lahars at Cotopaxi is strongly controlled by very small values for Coulomb friction μ (0.005-0.015). Finally, we apply the calibrated model to typical eruption scenarios of Cotopaxi (VEI 1 to >4) in order to enable a realistic lahar hazard representation.</p><p>Considering the rapid rise of the equilibrium-line altitude of tropical Andean glaciers together with reports on secondary lahars at the eastern flank of Cotopaxi without any clear trigger, we hypothesize a process-based link between the two phenomena.  Geoelectrical and refraction seismic field surveys near the glacier margin (5000- 5300 m asl) have been conducted in order to gain a better understanding of the structure, conditions and degree of freezing of the subsurface, which is dominated by loose pyroclastic material and interbedded lava layers. The tomography results are highlighted within the concept of permafrost degradation and accompanied material weakening as potential triggering mechanism for secondary lahars.</p><p>Here we show 1) a carefully calibrated numerical lahar model at Cotopaxi capable of reproducing previously non-respected effects such as confluence, erosion reach and propagation speed, and 2) first measurements addressing the role of glacier retreat on the formation of secondary lahars. Our results contribute to the multi-hazard risk assessment in the RIESGOS project funded by the German Ministry of Education and Research.</p>

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