Undulatory forcing an intruder through granular media: effects of frequency and packing fraction

Description

These files provide an example of the setup required to perform and analyze a numerical simulation of an intruder moving within a two-dimensional granular system under an oscillatory driving force. The simulations are conducted using the open-source DEM software LIGGGHTS, specifically version 3.1.0, coupled with the DESIgn framework, which enables two-dimensional simulations with cylindrical particles. The dataset includes an example of the initialization procedure, the main simulation setup, MATLAB/Octave scripts for post-processing the results, and the modified LIGGGHTS source code used to incorporate basal friction effects.

Steps to reproduce

1 – Basal Friction Folder 1 contains modified .cpp and .h files derived from the DESIgn code, extended to include static and dynamic basal friction. These files must be copied to LIGGGHTS/src and compiled with the DESIgn framework using LIGGGHTS 3.1.0. Detailed information on DESIgn is available at: https://herman.ocean.ug.edu.pl/LIGGGHTSseaice.html . 2 – Initialization Folder 2 provides an example for initializing a random particle distribution in a square domain. First, the user runs the Octave/MATLAB script Random_PositionGenerator.m with InputData.m, which generates the file Initialization_Position.init. This file must be placed in /DEM/init/. The user then configures the LIGGGHTS input script in.liggghts_init and runs allrun, producing a restart file in /DEM/res/restart/ for later intruder simulations. Note: A symbolic link named liggghts310 to the LIGGGHTS executable is required to execute allrun. During initialization, the computational domain is progressively reduced to a user-defined size to compact the particles. Example outputs are saved in /DEM/res/ and can be visualized using OVITO. 3 – Intruder Motion Folder 3 contains the setup for the intruder motion simulations. After completing Step 2, the restart file liggghts.restart from /DEM/res/restart/ must be copied to the restart directory of the main simulation. The user then modifies the input script in.liggghts_init_restart and launches the simulation via allrun. Initial results are written to /DEM/res/ and can be viewed in OVITO. Additional outputs include contact forces and particle stresses, stored in /DEM/res_force/ and /DEM/stresses/. 4 – Post-Processing Codes Folder 4 contains MATLAB/Octave scripts for post-processing the results from Step 3. The scripts loop over the output files, extract particle data, and assemble a final matrix. Analyses include global and local anisotropy, separation of strong and weak contact networks based on average contact force, force and velocity statistics, granular temperature calculation, and generation of force-chain files for visualization in OVITO. Each script targets a specific analysis task.

Institutions

• Universidade Estadual de Campinas

Categories

Funders

• Fundação de Amparo à Pesquisa do Estado de São Paulo

  Brazil

  Grant ID: 2018/14981-7, 2020/04151-7 and 2024/13981-4

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