Cratering by the oblique impact of a spinning projectile
Description
These files provide a complete example of the setup and workflow required to perform and analyze a numerical simulation of an oblique impact of a spinning projectile onto a granular bed. The simulation is conducted using the open-source Discrete Element Method (DEM) software LIGGGHTS. The methodology has been thoroughly tested, and the obtained numerical results show good agreement with experimental data reported in the literature, confirming the reliability of the setup. The dataset includes: An initialization example, illustrating all necessary steps for preparing the granular bed and positioning the projectile; and A main simulation case, which reproduces the actual impact event. Additionally, an Octave post-processing code is provided to facilitate the analysis of the simulation outputs. This code allows users to extract, process, and visualize quantities such as position, velocity, acceleration, and forces acting on the projectile during impact.
Files
Steps to reproduce
1. Mesh Generation In the Mesh.zip package: 1. Open the Python script located in the Mesh folder and adjust the variables to define the box (cylinder/bed) dimensions. 2. Execute the allrunMesh script inside the same folder. o This process will create a file named CylindricalBox.stl, stored in Mesh/DEM/STL/. o This STL file defines the boundaries of the granular bed and will be used in all subsequent simulations. o Once created, copy the CylindricalBox.stl file into the STL folders of all following simulation directories. 2. Particle Initialization In the Initialization.zip package: (a) Folder: Creation_particles 1. Run the allrunDEM script to execute the simulation. o This step inserts the particles into the domain and lets them settle under gravity. 2. After completion, copy the restart file liggghts12.restart from DEM/post/restart/ to the folder Eliminating_particles/DEM/post/restart/. (b) Folder: Eliminating_particles 1. Run the in.liggghts_elimination simulation by executing the allrunDEM_restart script. o This process removes particles located above a defined height threshold, producing a smooth and level bed surface. 2. Then, copy the file liggghts.restart_eliminated from Eliminating_particles/DEM/post/restart/ to Moving_projectile/DEM/post/restart/. (c) Folder: Moving_projectile 1. Run the in.liggghts_move simulation using the allrunDEM_restart script. o This step moves the projectile to its correct initial position for the main simulations. 2. Finally, copy the restart file liggghts.restart_move from Moving_projectile/DEM/post/restart/ to the folder Main_simulation/DEM/post_int/restart/. 3. Main Simulation In the Main_simulation.zip package: 1. After preparing the bed, copy liggghts.restart_move into Main_simulation/DEM/post_int/restart/. 2. Run the main simulation by executing the allrunDEM_main script. o To change the projectile’s release velocity, impact angle, or angular velocity, modify the corresponding variables in the in.liggghts_main input file. 4. Output and Post-Processing Simulation Output The simulation generates two sets of output data: 1. All particles and the projectile — recorded with a larger time step to reduce memory load. 2. Projectile-only data — recorded with a finer resolution for detailed motion and force analysis. Post-Processing with Octave An Octave analysis toolkit is provided to process and visualize the simulation results: 1. InputData.m — configure this file with the simulation parameters (e.g., bed properties, projectile characteristics, and initial conditions). 2. mainCode.m — extracts and organizes the raw data from LIGGGHTS output files. 3. Projectile_analysis.m — calculates specific quantities and models related to the projectile’s dynamics. 4. PlotData.m — produces .txt files and plots user-defined graphs such as position, velocity, acceleration, and force over time. All processed data and figures are automatically saved in the Results folder for further analysis or publication.
Institutions
- Universidade Estadual de Campinas