0.02dil

General information

0.02dil is a pseudo two-dimensional biaxial DEM simulation. It consists of
spheres constrained to move within the x-y plane. The left and right
frictionless walls are kept at a constant 703.5 N/m pressure, while the top
and bottom walls (\mu = 0.7) are moved inwards with constant strain.

There are 299 states in total.

The original data contained macroscopic and microscopic data. For macroscopic
data, the strain in the y-direction, and stress ratio are supplied. For
microscopic data, the particle positions, particle rotations and contacts
are supplied.

Derived quantities, such as volumetric strain, wall positions, etc, were
derived from the provided data. Wall positions were approximated from
particle positions and radii in the minima and maxima of the x- and y-
directions. You can do this to verify the provided y- wall strain.

The supplied global macroscopic properties file takes the form:

strain-stress-ratio.txt

The data within takes the following format:

<state> <strain in y-direction> <stress ratio>

The supplied state files take the form:

positions-<state>.txt
rotations-<state>.txt
contacts-<state>.txt

Particle positions

positions-<state>.txt contains particle positions and radii. The data within
takes the following format:

<particle id> <x-coordinate> <y-coordinate> <radius>

Particle radius does not change between states.

Particle rotations

rotations-<state>.txt contains particle rotational orientation. The data within takes the
following format:

<particle id> <rotation in radians>

Positive values correspond to anti-clockwise rotations.

Particle contacts

contacts-<state>.txt contains particle contact information. The data within
takes the following format:

<particle id 1> <particle id 2> <type of object 1> <type of object 2> <normal x> <normal y> <tangential x> <tangential y> <contact moment>

The different types of contacts are summarised below:

<type of object 1>	<type of object 2>	Contact type
1	1	Particle-particle contact
1	0	Particle-wall contact (typically). <particle id 1> refers to the particle in such contacts, <particle id 2> refers to a wall with 1=bottom, 3=top, 5=left, 7=right, other=unknown (contact me)

To obtain the total force acting at a given contact, you need to add the normal and
tangential components.

Specific intervals or states of interest

The following intervals contain behaviour that is deserving of considerable
study within the group.

Type	Interval (states)	Interval (strain)
Peak stress ratio	92	0.0349917175061380
Major unjamming (drop in stress ratio)	101-104	0.0384524366851653-0.0396060107668213
Greatest vortices observed	103-104	0.0392214850509556-0.0396060107668213