Contacts, motion and chain-breaking in a two-dimensional granular system displaced by an intruder
These files contain an example of the setup required to perform and analyze a numerical simulation of the motion of an intruder within a two-dimensional granular system. The simulation is carried out using the open-source free DEM software LIGGGHTS. Specifically, we make use of the 3.1.0 version to interact with the DESIgn code, that allows us to perform two-dimensional simulations considering cylindrical particles. The dataset contains an example case of the initialization, simulation, Octave and Matlab codes for post-processing the results, and the code implemented in LIGGGHTS to introduce basal friction effects.
Steps to reproduce
1 - Basasl friction) Folder 1 contains modified ".cpp" and ".h" files from the DESIgn code to include the effect of static and dynamic friction. The code should be added to the LIGGGHTS/src folder and compiled together with the DESIgn framework in LIGGGHTS 3.1.0. To instructions and details regarding DESIgn see https://herman.ocean.ug.edu.pl/LIGGGHTSseaice.html. 2 - Initialization) Folder 2 contains a simulation example to initialize the random particle distribution inside a squared domain. The simulation works like this: First, the user must run the "Random_PositionGenerator.m" octave code (using a specific "InputData.m" data) to randomly distribute the particles in a larger domain. This code will generate a "Initialization_Position.init" file, which needs to be inserted in the /DEM/init/ folder. Then, the user can adjust the LIGGGHTS script "in.liggghts_init" and run the "allrun" executable. This initialization will create a restart file on the DEM/res/restart folder that will then be used to simulate the intruder movement. NOTE: The user must create a symbolic link for the LIGGGHTS executable named liggghts310 to run the allrun code. This simulation shrinks the domain into a user-specified domain size to compact the particles. An example of the results are saved in the /DEM/res folder, and can be checked using the Ovito software. 3 - Intruder_motion) Folder 3 contains the setup of the main simulation. To start the simulation the user must perform step 2 of this outline. After running the initialization, the user must copy the restart file called "liggghts.restart" on the /DEM/res/restart folder of the main simulation. Then, the user must adjust the script file "in.liggghts_init_restart" according to its own interests. The simulation can be initialized by running the "allrun" executable. The first time-steps results of the simulation are shown in the DEM/res folder, and can be checked using the Ovito software. The simulation will also deliver the results for contact forces and particle stresses (see DEM/res_force and DEM/stresses folders). 4 - Codes) Folder 4 contains the Matlab/Octave codes to analyse the results from the simulation in step 3. The code loops over the output files extracting the details of each particle and saving them on a final matrix. The code will analyse: anisotropy levels in a global and regional space; separate strong and weak networks based on a average contact force; magnitude and average values of force and velocities and calculate the particles granular temperature; and will print a file to plot force chains on Ovito. Each code is separated according to its specific functionality.