Local particle refinement in terramechanical simulations

<b>Supplementary material:</b>This upload is meant as supplementary material to the article "Local particle refinement in terramechanical simulations" (Local particle refinement in terramechanical simulations). It contains scripts to run both bed generation and track tests, as well as data from 200 already run simulations.<br><b>Abstract</b>The discrete element method (DEM) is a powerful tool for simulating granular soils, but its high computational demand often results in extended simulation times. While the effect of particle size has been extensively studied, the potential benefits of spatially scaling particle sizes are less explored. We systematically investigate a local particle refinement method’s impact on reducing computational effort while maintaining accuracy. We first conduct triaxial tests to verify that bulk mechanical properties are preserved under local particle refinement. Then, we perform pressure-sinkage and shear-displacement tests, comparing our method to control simulations with homogeneous particle size. We evaluate 36 different DEM beds with varying aggressiveness in particle refinement. Our results show that this approach, depending on refinement aggressiveness, can significantly reduce particle count by 2.3 to 25 times and simulation times by 3.1 to 43 times, with normalized errors ranging from 3.4% to 11% compared to high-resolution reference simulations. The approach maintains a high resolution at the soil surface, where interaction is high, while allowing larger particles below the surface. The results demonstrate that substantial computational savings can be achieved without significantly compromising simulation accuracy. This method can enhance the efficiency of DEM simulations in terramechanics applications.<br>

<b>补充材料：</b>本上传内容旨在作为论文《土力学模拟中的局部粒子细化》（Local particle refinement in terramechanical simulations）的补充材料。它包含运行床层生成和轨迹测试的脚本，以及200个已完成模拟的数据。<br><b>摘要</b>离散元法（DEM）是模拟颗粒土的强大工具，但其高计算需求常导致模拟时间延长。虽然颗粒尺寸的影响已被广泛研究，但空间尺度上调整颗粒尺寸的潜在益处尚未得到充分探索。我们系统地研究了局部粒子细化方法在降低计算量同时保持精度方面的影响。首先，我们进行三轴试验，验证局部粒子细化下土体宏观力学特性是否得以保留；随后开展压力-沉陷和剪切-位移试验，将我们的方法与均一颗粒尺寸的对照模拟进行比较。我们评估了36种不同细化强度的DEM床层。结果表明，根据细化强度的不同，该方法可显著减少颗粒数量2.3至25倍，缩短模拟时间3.1至43倍，与高分辨率参考模拟相比，归一化误差范围为3.4%至11%。该方法在相互作用强烈的土壤表面保持高分辨率，而在表面以下允许更大颗粒。研究结果证明，在不显著影响模拟精度的前提下，可实现大幅计算节省。此方法能够提升土力学应用中DEM模拟的效率。