scholarly journals Effects of undercutting and sliding on calving: a coupled approach applied to Kronebreen, Svalbard

2017 ◽  
Author(s):  
Dorothée Vallot ◽  
Jan Åström ◽  
Thomas Zwinger ◽  
Rickard Pettersson ◽  
Alistair Everett ◽  
...  
Keyword(s):  
Element Model ◽  
Balance Model ◽  
Particle Model ◽  
Plume Model ◽  
Fracture Dynamics ◽  
Hydrology Model ◽  
Discrete Particle Model ◽  
Basal Sliding ◽  
Discharge Location ◽  
Glacier Motion

Abstract. In this paper, we study the effects of basal friction, sub-aqueous undercutting and glacier geometry on the calving process with six different models: a continuum-mechanical ice flow model (Elmer/Ice), a climatic mass balance model, a simple subglacial hydrology model, a plume model, an undercut model and a discrete particle model to investigate fracture dynamics (Helsinki Discrete Element Model, HiDEM). We also demonstrate the feasibility of reproducing the observed calving retreat at the front of Kronebreen, a tidewater glacier in Svalbard, during a melt season. Basal sliding and glacier motion is addressed using Elmer/Ice while calving is modelled by HiDEM. An hydrology model calculates subglacial drainage paths and indicates two main outlets at relatively different rates. Depending on the discharge, the plume model computes frontal melt rates, which are iteratively projected to the actual front of the glacier at subglacial discharge locations. This produces undercutting of different sizes, as melt is concentrated close to the surface for high discharge and is more diffuse for low discharge. By testing different configurations, we show that the geometry (frontal position and topography) controls the calving location while basal sliding controls the calving rate. Undercutting plays a key role in glacier retreat and is necessary to reproduce observed retreat in the vicinity of the discharge location.

scholarly journals Effects of undercutting and sliding on calving: a global approach applied to Kronebreen, Svalbard

2018 ◽  
Vol 12 (2) ◽  
pp. 609-625 ◽  
Author(s):  
Dorothée Vallot ◽  
Jan Åström ◽  
Thomas Zwinger ◽  
Rickard Pettersson ◽  
Alistair Everett ◽  
...  
Keyword(s):  
Element Model ◽  
Balance Model ◽  
Particle Model ◽  
Plume Model ◽  
Basal Friction ◽  
Fracture Dynamics ◽  
Hydrology Model ◽  
Discrete Particle Model ◽  
Basal Sliding ◽  
Ice Velocity

Abstract. In this paper, we study the effects of basal friction, sub-aqueous undercutting and glacier geometry on the calving process by combining six different models in an offline-coupled workflow: a continuum–mechanical ice flow model (Elmer/Ice), a climatic mass balance model, a simple subglacial hydrology model, a plume model, an undercutting model and a discrete particle model to investigate fracture dynamics (Helsinki Discrete Element Model, HiDEM). We demonstrate the feasibility of reproducing the observed calving retreat at the front of Kronebreen, a tidewater glacier in Svalbard, during a melt season by using the output from the first five models as input to HiDEM. Basal sliding and glacier motion are addressed using Elmer/Ice, while calving is modelled by HiDEM. A hydrology model calculates subglacial drainage paths and indicates two main outlets with different discharges. Depending on the discharge, the plume model computes frontal melt rates, which are iteratively projected to the actual front of the glacier at subglacial discharge locations. This produces undercutting of different sizes, as melt is concentrated close to the surface for high discharge and is more diffuse for low discharge. By testing different configurations, we show that undercutting plays a key role in glacier retreat and is necessary to reproduce observed retreat in the vicinity of the discharge locations during the melting season. Calving rates are also influenced by basal friction, through its effects on near-terminus strain rates and ice velocity.

Theory and Application of Fracture Dynamics in Concrete

2013 ◽  
Vol 333-335 ◽  
pp. 1803-1806 ◽  
Author(s):  
Yi Kun Zhang
Keyword(s):  
Particle Model ◽  
Load Carrying Capacity ◽  
Bending Tests ◽  
Notched Specimens ◽  
Fracture Dynamics ◽  
Load Carrying ◽  
Discrete Particle Model ◽  
Result Show ◽  
Lattice Discrete Particle Model ◽  
Tensile Fracturing

Lattice Discrete Particle Model (LDPM) provides accurate representation of concrete behavior under cycling loading both in tension and unconfined, confined, and hydrostatic compression. In this paper, LDPM is used to simulate tensile fracturing as demonstrated by the successful simulation of three points bending tests on notched specimens, the result show that it is able to reproduce pre-peak nonlinearity as well as softening post-peak behavior. It reproduces realistically the development of crack pattern due to tensile stresses and also could predict correctly size effect on specimen load carrying capacity.

Robust probabilistic calibration of a stochastic lattice discrete particle model for concrete

2021 ◽  
Vol 236 ◽  
pp. 112000
Author(s):  
Eliška Janouchová ◽  
Anna Kučerová ◽  
Jan Sýkora ◽  
Jan Vorel ◽  
Roman Wan-Wendner
Keyword(s):  
Particle Model ◽  
Discrete Particle ◽  
Discrete Particle Model ◽  
Lattice Discrete Particle Model

Modelling of Coating Thickness, Heat Transfer and Fluid Flow and It's Correlation with the TBC Microstructure for a Plasma Sprayed Gas Turbine Application

1998 ◽  
Author(s):  
P. Nylen ◽  
J. Wigren ◽  
L. Pejryd ◽  
M.-O. Hansson
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Gas Turbine ◽  
Coating Thickness ◽  
Spray Deposition ◽  
Temperature History ◽  
Particle Model ◽  
Barrier Coating ◽  
Discrete Particle Model ◽  
Turbine Component

Abstract The plasma spray deposition of a zirconia thermal barrier coating (TBC) on a gas turbine component has been examined using analytical and experimental techniques. The coating thickness was simulated by the use of commercial off-line programming software. The impinging jet was modelled by means of a finite difference elliptic code using a simplified turbulence model. Powder particle velocity, temperature history and trajectory were calculated using a stochastic discrete particle model. The heat transfer and fluid flow model were then used to calculate transient coating and substrate temperatures using the finite element method. The predicted thickness, temperature and velocity of the particles and the coating temperatures were compared with these measurements and good correlations were obtained. The coating microstructure was evaluated by optical and scanning microscopy techniques. Special attention was paid to the crack structures within the top coating. Finally, the correlation between the modelled parameters and the deposit microstructure was studied.

Fractality of Simulated Fracture

2009 ◽  
Vol 409 ◽  
pp. 154-160 ◽  
Author(s):  
Petr Frantík ◽  
Zbyněk Keršner ◽  
Václav Veselý ◽  
Ladislav Řoutil
Keyword(s):  
Numerical Model ◽  
Elastic Plate ◽  
Model Simulation ◽  
Element Model ◽  
The Other ◽  
Particle Model ◽  
Discrete Element Model ◽  
Fractal Nature ◽  
Discrete Elements ◽  
The Impact

The paper is focussed on numerical simulations of the fracture of a quasi-brittle specimen due to its impact onto a fixed rigid elastic plate. The failure of the specimen after the impact is modelled in two ways based on the physical discretization of continuum: via physical discrete elements and pseudo-particles. Advantages and drawbacks of both used methods are discussed. The size distribution of the fragments of the broken specimen resulting from physical discrete element model simulation follows a power law, which indicates the ability of the numerical model to identify the fractal nature of the fracture. The pseudo-particle model, on the other side, can successfully predict the kinematics of the fragments of the specimen under impact failure.

scholarly journals Glaciological studies on Nelson Island, South Shetland Islands, Antarctica

1995 ◽  
Vol 41 (138) ◽  
pp. 408-412 ◽  
Author(s):  
Ren Jiawen ◽  
Qin Dahe ◽  
J. R. Petit ◽  
J. Jouzel ◽  
Wang Wenti ◽  
...  
Keyword(s):  
Accumulation Rate ◽  
Local Environment ◽  
High Viscosity ◽  
Force Balance ◽  
South Shetland Islands ◽  
Balance Model ◽  
Shetland Islands ◽  
Ice Cap ◽  
Basal Sliding ◽  
Marine Air

AbstractThe ice cap on Nelson Island in the South Shetland Islands, West Antarctica, was studied between 1985 and 1989. The ice cap has an average thickness of 120 m. it is temperate, exists under the sub-Antarctic maritime climate and almost completely covers the island. Owing to intense percolation of meltwater (and, to some extent, liquid precipitation), the snow-firn layer is in the soaked facies, with a firn-ice transition at a depth of 25-26 m at the summit. A force-balance model suggests that the ice is almost linearly viscous but has a high viscosity. The model further suggests that basal sliding makes a larger contribution to the ice movement than does ice deformation. From 1970 to 1988. the average accumulation rate was 120 kg m−2a−1at the centre, and between 1985 and 1989 the equilibrium-line elevation averaged 110m a.s.l. Analysis of chemical impurities in the surface snow suggests that the precipitation source is mainly local marine air masses and that human activity has already exerted a detectable influence on the local environment.

scholarly journals Research on the Tunnel Excavated In Urumqi Glacier No. 1, Tianshan Glaciological Station, China

1987 ◽  
Vol 33 (113) ◽  
pp. 99-104 ◽  
Author(s):  
Huang Maohuan ◽  
Wang Zhongxiang
Keyword(s):  
Melting Point ◽  
Shear Strain ◽  
Maximum Shear Strain ◽  
Ice Surface ◽  
Basal Sliding ◽  
Glacier Ice ◽  
Glacier Motion

AbstractA tunnel was excavated in Urumqi Glacier No. 1, at the Tianshan Glaciological Station. Ice temperature, ice displacement, deformation, and basal sliding, etc. were observed at regular intervals. It is shown that the temperature near the glacier bed is close to the melting point and that the largest proportion of the overall glacier motion is within the lowermost ice layers. The glacier ice is in a state of compression. The maximum shear strain increases towards the entrance of the tunnel, corresponding to the change in slope of the ice surface, and also towards the bedrock.

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