Difference between revisions of "Snow documentation"

From Yade

Line 5: Line 5:
 
'''Introduction'''
 
'''Introduction'''
   
A novel Discrete Element Method (DEM) employing polyhedral elements based on experimental set-up parameters is developed. It is implemented in an algorithm that simulates a dynamic model of creep deformation based on observed snow grains packing.
+
A novel Discrete Element Method (DEM) employing polyhedral elements based on experimental data is developed. It is implemented in an algorithm that simulates a dynamic model of creep deformation based on observed snow grains packing.
 
The model uses a grain-scale algorithm that requires geometrical input parameters from a
 
The model uses a grain-scale algorithm that requires geometrical input parameters from a
 
three-dimensional (3D) scans of the observed snow grains packing. The 3D high resolution image was obtained from scanning a cylindrical snow specimen using Synchrotron X-ray Diffraction
 
three-dimensional (3D) scans of the observed snow grains packing. The 3D high resolution image was obtained from scanning a cylindrical snow specimen using Synchrotron X-ray Diffraction
 
Contrast Tomography (DCT) technique.
 
Contrast Tomography (DCT) technique.
   
[[File:xrays.jpg]]
+
[[File:xrays.jpg|800px|thumb|left|A scanned ice grains packing.]]
   
  +
A reconstruction algorithm is used to convert tomography data into a set of grains, represented as a set of parallel layers. The orientation of layers correspond to crystallographic planes, and the layers can slide relative to each other according to a viscous creep law, thus simulating the deformation of mono-crystaline ice grains.
In the mean time the DEM algorithm is implemented YADE in the older version of yade. The algorithm converts each grain image into polyhedral elements that consist of several facets.
 
   
  +
[[File:Grain34.jpeg|800px|thumb|left|Geometry obtained after tomography (left), and polyhedral representation in Yade (right).]]
[[File:Grain34.jpeg]]
 

Revision as of 15:52, 1 October 2010

By Alsidqi Hasan

This development is supported by the French National Agency of Research (ANR), via the "Snow White" project (ANR-06-BLAN-0396-01).

Introduction

A novel Discrete Element Method (DEM) employing polyhedral elements based on experimental data is developed. It is implemented in an algorithm that simulates a dynamic model of creep deformation based on observed snow grains packing. The model uses a grain-scale algorithm that requires geometrical input parameters from a three-dimensional (3D) scans of the observed snow grains packing. The 3D high resolution image was obtained from scanning a cylindrical snow specimen using Synchrotron X-ray Diffraction Contrast Tomography (DCT) technique.

A scanned ice grains packing.

A reconstruction algorithm is used to convert tomography data into a set of grains, represented as a set of parallel layers. The orientation of layers correspond to crystallographic planes, and the layers can slide relative to each other according to a viscous creep law, thus simulating the deformation of mono-crystaline ice grains.

Geometry obtained after tomography (left), and polyhedral representation in Yade (right).